I don’t use Windows anymore (Pop_os and FreeBSD) but never had an issue with how the fonts rendered. The site doesn’t seem to indicate anymore information either.
Windows biases for a sharper text appearance, whereas Mac is much smoother. I can see why some folks prefer the sharp look, but fonts on Windows often look nothing like what the designer intended. Mac is a lot more true to the font design.
Honestly, I prefer the Windows sharpness much to the aesthetic and font design that the author of the font wants. Fonts are a nice for styling a document or website, but in the end the text is designed to be read, not to be art.
If the designer only tested on macOS, I don't think this has anything to do with what the designer "intended". It just shows a lack of testing on other platforms, something that happens quite often (i.e. when dealing with scrollbars [1]).
Personally, I dislike the vague, blurry rendering macOS uses. Macs usually compensate for their weird, blurry, bold rendering with high-resolution screens, but on lower resolutions I really dislike the way fonts look on macOS.