Okay I finally fixed all the errors. I was getting loooots of errors. Most of them were caused by missing includes after disabling unity like Rumbleball said.
After that I started getting unresolved external error because of one of my static methods. Static method was using a templated method of another class. I created a non templated version of this method for this static method and now my compile times are around 6 seconds. Before it was 13-14 seconds at best, and usually I was waiting 20 to 60 seconds, sometimes up to 300 seconds.
I also converted as much includes to forward declerations in my header files.
Finally, I created a seperate .h file for structs and enums so they won’t cause any problems because of forward declerations.