Hey @XeoNN ,
As stated above, if it's kicking you out the game in both TruckersMP and singleplayer, it's probably something to do with the files that you currently have downloaded.
If you redownload the ProMods files (and the DEF file) and replace them in your Documents > Euro Truck Simulator 2 > mod folder, and then try launch ProMods, hopefully that should fix your issue.
Do note, that if it's kicking you out of TruckersMP as soon as you try to join ProMods, then it's probably something to do with the files downloaded.
Hopefully this does answer your question.
Kind Regards,
JamesS014
TruckersMP Game Moderator