> I still get GCC 6.3.0 detected and MINGW32 is not set. Any advise ?
Follow the advice in updating build tools
As for your "MINGW32 is not set" error, it sounds like you have a conflict between CONFIG_ARCHITECTURE and PTR64. If you don't specify them at all then they should default the correct way.
A simple way to check would be open a standard windows command prompt and run these commands
if that does the same thing then for x86 builds you want set PTR64=0 and for x64 builds you want set PTR64=1, while set CONFIG_ARCHITECTURE=x86 or set CONFIG_ARCHITECTURE=x64
If you change CONFIG_ARCHITECTURE then you need to run \msys64\win32\env.bat again, if you change PTR64 then you ought to run make REGENIE=1 again.