PLEX_CLAIM The claim token for the server to obtain a real server token. If not provided, server will not be automatically logged in. If server is already logged in, this parameter is ignored. You can obtain a claim token to login your server to your plex account by visiting https://www.plex.tv/claim
Thanks, I logged out from all clients, restarted the server with a new PLEX_CLAIM and it worked, Plex was able to idenfity the server and I’m now able to add the library.