Windows VM

You can obtain a Windows virtual machine image from Microsoft (with a 90-day limit). See this blog: https://developer.r-project.org/Blog/public/2021/03/18/virtual-windows-machine-for-checking-r-packages/

MinGW-32 and MinGW-w64

MinGW-32 and MinGW-w64 are two different compilers. That is to say, MinGW-w64 is not the 64 bit version of MinGW-32.

System32 and SysWOW64

These are default directories for storing DLLs. It is funny that System32 is for 64-bit DLLs and SysWOW64 is for 32-bit DLLs.