Please follow this solutions:
Open TruckersMP in Administrator Mode.
Install the available updates (only the first run with Ultrasurf), wait for it to finish and Launch button appears.
In order to verify your game cache, go to your 'Library' and find 'Euro Truck Simulator 2'.
Once you find it, 'Right Click' and go to the 'Properties ' tab.
This will open up the properties tab. Go to the third sub-tab that says 'Local Files' where you will be presented with the fo