Jemand hat das gleiche Problem wie ich.
Diese hilfreiche Antwort hat er bekommen. Es hat bei ihm dann funktioniert. Nur ich werde nicht schlau daraus.
You have to check if the path where you installed everything is correct. The sounds in the "GameData/Sounds" folder and the 3d and physics files under the "GameData/Teams" folder.
Then you should have a gdb file that contains the correct filters (i.e. if your .car file contains the line "Classes=MYFILTER1, MYFILTER2", then you must have in your "GameData/_A_NAME_.gdb" file the line "MYFILTER2 = _WHAT_YOU_SEE_IN_GAME_"

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Antwort:
I understood how it works, I tried what you said and it functioned perfectly. I did not have a .gdb file with the proper class filters. Thanks very much to kk08 and harvestmouse.
The "Classes=" lines and the ".GDB files" are very important when it comes to adding mods.
Ich sehe gdb files - was soll ich daran ändern?