There was a cmake 3.13 installed on the machine which does not support any VS 2019 generator. I replaced it with the latest - 3.14.3. This supports a VS 16 2019 (not 17). So, finally, with the command (the way to declare the architecture has also changed to using the -A option)
cmake -G"Visual Studio 16 2019" -Ax64 ..
the build files were created succesfully, afterwards the vstsdk.sln could be build and the generated .vsts seem to work in Cubase 10.
Thanks a lot.
Best regards,
Uli