Open the Airtame app (available in Managed Software Centre on Mac).
Find the ID on the meeting room screen:
And type it into the app:
And then click Share Window or Share Screen.
If the room has a Camera, you can join a Teams meeting by clicking Join Call.
The first time you try to share from a Mac, you will need to allow screen sharing for the app by going to
System Settings > Privacy & Security > Screen & System Audio Recording
and allowing the app: