On Windows, Principia officially supports recent builds of Windows 10 and newer. Generally if Microsoft still provides a version of Windows with updates then it is supported and Principia should work on it (and if it does not, this is a bug you can report).
While older versions of Windows are not officially supported, they may still be compatible. Principia is confirmed to run as far back as on a fully updated version of Windows 7, but is not officially supported and may stop working at any time.
Principia is now built against the UCRT, which is a newer C runtime than the ancient MSVCRT. It is included by default on Windows 10 and newer, but should be available on older versions of Windows if you are fully up-to-date with updates as far back as at least Windows 7. If you get an error about ucrtbase.dll
not being found, then you need to install all the available updates from Windows Update up until the Windows version's EOL date.
Only 64-bit Windows builds are provided as practically any hardware you can find nowadays is 64-bit, and any remaining 32-bit hardware is most likely better suited running a lightweight Linux distro.