TruckersMP does not support the latest game version of Euro Truck Simulator 2 and American Truck Simulator yet.
Check out the following guide on how to downgrade so you can keep playing on multiplayer: How to downgrade
Before creating a support ticket about your game version not being supported in TruckersMP
SCS released an update for ETS2 and ATS.
We do not support the latest version of these games yet.
You need to wait until we release a game update in order to play the newest version of ETS2/ATS in our Multiplayer.