I am not a complete beginner in ETS2 modding. I edited a mod (imported .pmds and exported them again a year ago). I had issues too but I did it somehow. But now I am stuck.

I get the following error message: "Error: Can't run conversion tools or there were errors by converting!"
I already now, how I can get the exported files: When I press >>> Pack Mod <<< a folder in the conversationTools will be created: conversationTools/rsrc/@chached
In that folder I can find the .pmd and .pmc files.
But I want to know why it does not work with the Blender Tools directly like in the tutorails. It's so annoying because I have a quite good model and I really want to know the reason for that error. I can't find any log files other than those in the picture.
- I watched the tutorials three times
- I did a very easy mod (just a cube as a frontgrill)
- I used three different Blender versions: 2.91.2 (Steam), 2.81 (Steam), 2.81 (non-Steam)
- I used two different conversation Tool versions (2.12, 2.10)
Can someone help me? Thank you!