Sessions are empty. What do I need to turn on?

Accounting is configured separately from authentication, so a network that authenticates perfectly can still be sending Passbeam nothing about sessions. Two things have to be true.

Add Passbeam as an accounting server on port 1813 in the same RADIUS profile you already point at us — both of our addresses, exactly as you did for authentication, with the same shared secret. In UniFi it is the Accounting Servers box directly under the authentication servers. Set the update interval to 300 seconds if your equipment asks.

Open the firewall outbound on UDP *and* TCP 1813. Two rules, not one. A rule written for a single protocol looks right and passes nothing, and this is the most common reason a correctly-configured profile still sends nothing — the equipment tries, gets no answer, and gives up without showing you an error.

After that, a session appears the next time a device joins. Devices already connected when you turn it on may not appear until they reconnect, because the equipment reports a session starting and has nothing to say about ones that started before you asked.

If it still stays empty, the authentication log is the thing to check: if devices are not authenticating either, the problem is not accounting.