I don’t understand what the essence of the error is, specifically if I can’t export the project, does it give an error?

Question

Unity

I don’t understand what the essence of the error is, specifically if I can’t export the project, it gives an error.
I ask you to look at my unity project, because I think that I won’t fix this mistake myself, and people here who know more about the engine and about C# than I do.

Here is the link - https://mega.nz/file/J5snla7Q#oZ636mEXMP2D4j6CjlYt...