@Elias11022 The project at GitHub is compiled with the main project as if it was a module instead of a plugin as it is and usually that will work when packaging. I am not certain why that error is happening, but I guess something in that Install.md is not accurate anymore. The correct way would making a batch per UE4 release (just in case something changes with the build tool) and compiling the plugin putting it into the UE4 installation structure as any other plugin acquired from the Marketplace and inside the project when enabling it will be enough.
I will probably make a video showing how to do it. I just need some time to prepare it because currently I am unable to use a computer since I got my arms immobilized because a issue with my spine. Give me at least 3 more days to get into this.