How to create a TouchGFX Project for Custom Board?

Hello Everybody, I am trying to create a TouchGFX project for my custom board. I follow embryonic.dk's video on Youtube. However I couldn't manage to build a project. I received errors in the first image. It says No such file or directory for app_touchgfx.h. However, It is in the project. The interesting thing is when I check it's properties the exclude resource from build option was selected.I deselect it. But I receive more errors. I tried to deselect exclude from build option for every folder in the project manually but it didn't work. How can I create a TouchGFX project for my custom board? I was not expecting that it's gonna be that hard. I don't have much knowledge. I am using STMCubeIDE version 1.10.1, TouchGFX generator version 4.20 and TouchGFX Designer version 4.20.