As the installer now ships with several "mapset" files, here is a list of what each of them is for. (in general 6*.img files are map files, 7*.img and 9*.imgfiles are contourlines files. 8*.img for VeloMap only the buildings. OpenMTBMap always has buildings included).
mapset  --- for maps without contourlines integrated. (e.g. mapset.img / mapset_mdr.img / mapset.tdb)
mapsetc --- Theese are the mapset files which integrate the 20m contourlines into the map (6*.img & 7*.img), For VeloMap also buildings are included (8*.img)
mapset10 --- Theese are the mapset files which integrate the 10m contourlines into the map (6*.img & 9*.img), For VeloMap also buildings are included (8*.img)
mapsetx --- Theese are the mapset files which do not integrate the contourlines into the map (6*.img only). For VeloMap also no buildings.
mapsetz --- Theese mapset files are for you if you want to have a separate 20m equidistance contourlines only map. For compatibility with mapsetx maps when used on the same device - they use a different FID. (7*.img)
mapsety --- Theese mapset files are for you if you want to have a separate 10m equidistance contourlines only map. For compatibility with mapsetx maps when used on the same device - they use a different FID. (9*.img)
mapsetb --- Theese mapset files are for you if you want to have the separate buildings for the VeloMap. (8*.img) - there is only one typ-file - build*.typ
mapsetxb -- Theese mapset files are for you if you want to have a map including 20m contourlines, but wihtout buildings (If you chose 10m I assume you want to have buildings - sorry I cannot add that too).


Which .typ file should I choose (openmtbmap)?
*clas --- Classic - optimized for Vista/Legend/edge_705 series - red/yellow streets - rather thin for lower DPI Garmin devices
*cllg --- Classic Legacy - Like above optimized for Vista/Legend/edge_705 series - blue-green-red-yellow streets
*wide --- high contrast layout, like classic but with white forest and wider streets/lines - optimized for Oregon/Colorado dull displays - red-yellow streets
*wdlg --- same as above - but blue-green-red-yellow streets
*easy --- Simple Layout with (nearly) no additional info over traditional topo maps. Same width as Classic. No add. lines for (mtb:scale(:uphill)/cycleway=*/sac_scale) 
*hike --- Similar to easy but fully optimized for hiking. 
*wint --- Winter - like hiking layout - but optimized for Winter Sports (does not show mtb/bicycle informations). Shows sledge routes, nordic skiing and skitouring routes.
*fenx --- Fenix - similar to Wide Legacy but optimized for Fenix series 5/6/7 watches which can only show 64 colours
*topo --- Simple topopgraphical map style - Easy to understand - high contrast.

*trad --- Mapsource/Basecamp/Qlandkarte_GT/Desktop --- General big screen/resolution layout. It is the easiest to understand layout and optimized for big screens (800x600 or bigger). Street colors similar to google maps. Medium contrast - therefore bad for GPS use.


Which .typ file should I choose (velomap)?
*velo --- The layout to be used on your GPS Device. High Contrast - for lower DPI devices - red-yellow streets
*vllg --- Velo legacy - same as above - but blue-green-red-yellow streets
*velw --- Wide Velo - The layout to be used on your high DPI - e.g. Oregon _ GPS Device. Same but wider lines compared to velo - red-yellow streets
*vwlg --- Same as above - the Wide Legacy Layout for Velomap - but blue-green-red-yellow streets
*trdn --- Mapsource/Basecamp/Qlandkarte_GT/Desktop --- General big screen/resolution layout. It is the easiest to understand layout and optimized for big screens (800x600 or bigger). Street colors similar to google maps. Medium contrast - therefore bad for GPS use.
*race --- The best layout for race/road cycling. High Contrast - red-yellow streets
*vfnx --- Fenix similar to velo Wide Legacy but optimized for Fenix series 5/6/7 watches which can only show 64 colours
*topv --- Simple topopgraphical map style - Easy to understand - high contrast.

SH Script to create gmapsupp.img out of the .exe file directly:
https://github.com/btittelbach/openmtbmap_openvelomap_linux


To view  the maps and send them to the GPS I recommend you install Qlandkarte GT
(or install Mapsource using Wine).



Other solutions:

How to create a gmapsupp.img for GPS upload - use the create gmapsuppp bash files - or:
1. Get mkgmap - either compile from source (it's actually quite easy) - or get it from mkgmap.org.uk http://www.mkgmap.org.uk/download/mkgmap.html (use latest unstable/developer version) or (and this is not recommended) - install it from your packet manager (e.g. sudo apt-get install mkgmap or sudo aptitude install mkgmap). In the case where you install it you will need to find out where mkgmap.jar is installed (e.g. locate mkgmap.jar) - however I repeat, I don't recommend to install it via packet manager as usually it will be too outdated!

a) You need to send the maps to the GPS using the same FID as the 6*.img have. so i.e. for Velomap Austria the 6*.img are called 663500**.img. 6635 is the FID. (for openmtbmap Austria it would be 636500**.img and hence FID is 6365). That's the FID that you should use in general. If you use another FID (never two maps may have the same FID on your GPS Device) you need to change the FID for the .typ-file with GMT: 
gmt -wy %FID% name_of_typfile.TYP >NUL

b) Create the gmapsupp.img with mkgmap. If you want to integrate contourlines the command could be like (for Austria):
java -jar -Xmx2000M mkgmap.jar --family-id=6365 --index --description="mtbmap_austria_srtm" --series-name="mtbmap_austria_srtm" --family-name="mtbmap_austria_srtm" --product-id=1 --gmapsupp 6*.img 7*.img name_of_typfile.TYP
--index (if you are low on memory, or don't want to have address search enabled for the map, simply remove it)
-XMx  -- here you can set the memory available to java. If you don't need an address index 128 is enough. Otherwise it needs to be at minimum of around the total size of all 6*.img and 7*.img files.
"mtbmap_austria_srtm" -- this is just an example name. exchange it with a name of your choice so you know which map is active/not active on your GPS device.

If you don't want to include the contourlines - run this command instead: java -jar -Xmx2000M mkgmap.jar --family-id=6365 --index --description="mtbmap_austria" --series-name="mtbmap_austria" --family-name="mtbmap_austria" --product-id=1 --gmapsupp 6*.img name_of_typfile.TYP

c) place that gmapsupp.IMG into the folder /garmin on your GPS (micro) SD Card. On newer Garmin GPS devices you may rename it, and put several gmapsupp.IMG files into /garmin folder on the SD. On nearly all Garmin GPS it's best to take out the SD card, put it into a cardreader, then transfer the gmapsupp.img and then reinsert the microSD-card. On newer Garmin outdoor GPS (all touchscreen, or ~2011 or later) you can rename the gmapsupp.IMG as you like, and put other/more gmapsupp.IMG onto the SD. E.g. alps.IMG, Germany.IMG and so on. However best do not use special symbols in the name, and no spaces.

Note: All mapfiles are called 6*.img. All contourlines are called 7*.img. So when calling up mkgmap.jar to create the gmapsupp.IMG - just drop 7*.img if you don't want to have contourlines included. Or drop 6*.img if you want a contourlines only gmapsupp.IMG.
