Server/Library I definitely have access to is telling me I don't have access/am not authorized

[OttoKerner]

Your sister needs to update her server software version.

Plex Media Server - Security Update

As a follow-up to the original report and in an abundance of caution due to a population of servers still on an affected Plex Media Server version (versions 1.41.7.x to 1.42.0.x), we have made adjustments for access to affected servers. Specifically, other users to which the server owner has granted access to the server will not be able to connect to it while the server is running an affected version. Once the server is updated to a fixed version, other users will be able to access again. Server…