@Freddy00 Driver installation with sudo ~/Retropie-Setup/retropie_setup.sh should work. If you want to review the compile log see zless ~/~/RetroPie-Setup/logs/rps_2019-03-15_194311.log.gz when back on commandline (your date and time may vary).

You can type lsmod alone, you should spot the mk_arcade... driver loaded.
(If the command still is not found you should install kmod, but it should be already there, so there should no need to issue sudo apt-get install kmod.

Then, and only then when lsmod shows the module, proceed with https://github.com/recalbox/mk_arcade_joystick_rpi#auto-load-at-startup edit the mk_arcade_joystick.conf and change the map=1 to map=1,2. Save the file, reboot and then you can configure your joysticks with emulationstation.

If you use the retropie_setup.sh method you should succeed. If not please do post the build log as noted above.

PS: I would refrain from following the Github tutorial from A to Z, a) it is tailored towards another Retro-Distro (Recalbox), b) if you get stuck it's hard to help and c) last but not least this is a forum about Retropie-Distro (and not Recalbox).