This mod (and usually every mod) has compatibility issues with other car mods, especially if the author of the mods isn't the same.
This is happening because they all modify the script of the car engine sounds, which the launcher doesn't like.
I recommend you create a folder called CommandLine.txt in the same directory as your launcher & type in the following command: -allowignoremodconflicts
I think this might have some errors when in-game, such as one of the cars not playing the engine sounds, but should work.
I hope this helps!