RingCentralForTeamsDesktopPlugin

You see this option only if you are a member of at least one call queue.
If you are just a Super Admin or a call queue manager, but not a call queue member it will not be visible. This would be the first thing to check.

If you are indeed a member of a call queue then I expect that you find the toggle in Teams > select the Embedded app > top right corner you should see a cogwheel for Settings.