is the Teams Outlook for Mac Add-In only active when i have a Mail Account inside Office 365?
When I use Outlook with my Mail Account that is hosted on on-premise Exchange, the Add-In is not appearing. With my Account that is hosted inside Office 365. I can use and see the Add-In without Problems.
Yes, the PC version can use the primary account's Teams meeting entry to create meetings on extra Accounts since it uses the old Add-ins installation. I'm pretty sure Mac client uses the cloud add-in framework which is tied to an account so it would prevent you from accessing the addin from another account. If I had my mac still I could confirm this, but I'll look around to see if I can find where that is, but pretty sure that's what it going on here.
We tested with the same primary Accounts on Windows and Mac. All people on Windows can see this Add-In and they don't have a Office 365 Mailbox. The Windows User have they normal Exchange on-premise Account as primary