It's been a few years since I used a Mac, but even then resource forks weren't something you'd see outside of really old apps or some strange legacy use case, everything just used extended attributes or "sidecar" files (e.g. .DS_Store files in the case of Finder)

Unlike Windows or Linux, macOS takes care to preserve xattrs when transferring the files, e.g. their archiver tool automatically converts them to sidecar AppleDouble files and stores them in a __MACOS folder alongside the base file in the archive, and reapplies them on extraction.

If course nothing else does that, so if you've extracted a zip file or whatever and found that folder afterwards, that's what you're looking at.