Aaaah, these CPack files are a leftover which are not used right now. I planed to use it as it seemed to be a very straightforward way to create a cross-platform installer at first but it was not. This has been discussed in here a bit CMake: COPY_PLUGIN_AFTER_BUILD, CLion and building plugin installers with CPack
I went back to an approach with Inno for Windows and Packages for macOS but left the files there in order to maybe give it another try – but I think this probably won’t happen 