I already fixed it. I found out I had a script with a class name "CharacterController" in my project. After renaming my class everything seems to work just fine :-)
The plugin is not working, how can I fix this? As as soon as I import it it throws errors to me. This is what I have done:
I'm on the latest Unity version 2021.3.10f1 and using it on Windows 11
Bought Behavior Designer from Unity Asset Store
Package Manager > Download and Import
I get these...