Fixed it by running the launcher, clicking play (no DirectX or OpenGL) and then running Euro Truck Simulator 2 (also without DirectX or OpenGL). This crashed my pc giving it a black screen and after I restarted it the mod would run the game.
When I click 'play' on the ETS2MP launcher (where the launch with DirectX and OpenGL options are) it crashes and says 'not responding'. I have tried starting as administrator several times and uninstalled and reinstalled the Euro Truck Simulator 2 steam file and multiplayer mod file, multiplayer directory is: D:\Steam\steamapps\common\Euro Truck Simulator 2 Multiplayer and Winter mod are installed. Beta selection is set to none. Operating system = Windows 10