Just to let you know, if you join a TV session on a newer MAC OSx, sometimes you may get the issue where you cannot click or control anything. This is because the MAC accessibility settings are locked down.
To sort this and take control follow below steps.
Select apple symbol (top left of screen)
Select “System Preferences”
Security & Privacy
Select lock symbol – enter username and password of logged I user or if required admin account
Tick Team Viewer - Desktop