"Debug" info was great, thank you!
Close to the finish line I had some issues with my firewall, saying suspicous file needs to be deleted (some gio-2.dll). After adding an exception to the folder I could not get it running, so I did everything again from scratch.
Regarding Visual Studio: I needed to choose a developer package otherwise the x64 native tools command line tool was not available.
Ctest was successful except the mentioned 5 packages in the instructions (also under "Debug" option).
Ok, final sprint: typing "C:\Cadabra\bin\cadabra2-gtk" resulted in
"Fatal Python error: initfsencoding: unable to load the file system codec ModuleNotFoundError: No module named 'encodings'
Checked on solutions: a) instally Python as admin, b) set path variable during installation, c) set path variable and PYTHONHOME variable manually.
Did all 3, none worked. Do you have any advice?
At least command line with "python C:\Cadabra\bin\cadabra2" is working. ;)