Hi @TorkkeliM
In this case, we firstly recommend you contact with your Teams admin to check that the user has a meeting policy that permits the Outlook Add-in. Allow the Outlook add-in is a per-user policy and applies before a meeting starts. This setting controls whether Teams meeting can be scheduled from within Outlook. If you turn off this, users are unable to schedule Teams meeting in Outlook. To check this setting, you need to go to Teams admin center, click Meetings->Meeting policies->General, you will find the settings here like the following picture:
In addition, please make sure that all available updates for Outlook desktop client have been applied and then restart Teams client and Outlook client to see if it can be fixed.
If the above suggestions is not work for you. I have some questions that need you answer to narrow down this issue:
1.Can you schedule Teams meeting normally in outlook web App?
2.Have your enabled Teams meeting add-in in Outlook client?
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