Plex keeps showing "not authorized"

[OttoKerner]

You need to claim it again, in order to restore access to it.

You need to reclaim your server, but don't dare to touch the Windows Registry

Warning: During these steps your Windows Plex server will be removed from any plex.tv account it has been connected to. The result will be that you won’t be able to acess it normally, unless you re-claim it. So you have been told to perform this procedure https://support.plex.tv/articles/204281528-why-am-i-locked-out-of-server-settings-and-how-do-i-get-in/ in order to solve a problem accessing your server – but doing so requires you to edit the Windows Registry. I can understand that this c…

After importing the registry file, follow the link to the “new claiming requirement for Windows” and follow its instructions.