For all I can find, Plex’s Discover feature is available to all accounts – except for managed users.
From https://support.plex.tv/articles/discover/
Note : The Discover source is not available for Managed Accounts.
There’s a feature suggestion asking for Plex to close this gap (=enabling support for Discover for managed users too). If that’s what you’re looking for, you might want to vote/comment in that thread in order to help us avoid distracting or cannibalizing votes.
