I’ve tried linking tidal hifi again multiple times, rebooted the server (and relaunched it too), rebooted my iPhone (latest iOS 12.3.1) and tried to close and launch the Plex app (have lifetime Plex pass) multiple times too. That and the server have latest available updates. This is very frustrating, I’ve only gotten it to work a few times and it stops working after a few days. Now I can’t get it to work at all, it keeps showing this screen no matter what I do (listed above).
What should I do to get it to work? Thank you in advance.

just like the instructions on Plex site says, through the settings page: