Seems the change to Plex-pass being required client-side, not server-side, is a new thing related to ditching mobile Sync. By the wording, it sounds like they didn’t ENFORCE that the client needed it before now. They must’ve updated that ** Downloads for Windows, macOS, Linux Desktop** link yesterday.
Either way, it sounds like the client needing it to download is the intended behavior, which is not what you see here.