Users get the warning that they must be part of the team to use the chat even though they appear to be part of the team
It appears that automatically created teams are Deactivated by default meaning that members can't access everything fully until the teacher activates the team
Fortunately it is very simple to activate the team as shown in the following web page
Class Teams Activation
All Class Teams provisioned by Microsoft School Data Sync are now deactivated for students. This means the students can only access the team once the teacher has pressed the activate button.
One huge benefit is that students cannot have conversations in the team until it becomes activated. When hundreds of teams are created for each school every academic year, it’s hard to monitor all of them. With this new setting, teachers only have to monitor the conversations in teams that they have activated.
Prepare Class Teams in Advance
The activation step allows teachers to prepare content in the team before it goes live to students. Prepare your class notebook and assignments in advance before activating it at the start of term.
How to Activate the Team
It’s really simple, just click the “Activate” button shown below and confirm. Students will then have instant access to the team.