Installing MingW-w64 without administrator privileges
The installer for MinGW-w64 is an exe file that needs adminstrator privileges when executed.
Without adminstrator privileges, MinGW-w64 can be installed from a .7z file that can be found on https://sourceforge.net/projects/mingw-w64/files (Subdirectory Toolchains targetting Win64 -> Personal Builds -> mingw-builds -> version… -> threads-win32 -> seh -> xyz.7z)
TODO
Apparently, the above link does not come with the latest version of GCC - it seems that a MinGW environment with the lastest GCC version can be downloaded from https://winlibs.com/