Check if the Add-in is Disabled
Open Outlook
Go to File
3. At the bottom, in Manage: COM Add-ins
4.Look for:
Microsoft Teams Meeting Add-in for Microsoft Office - Enable this add-in
Step 2: Re-enable Disabled Add-ins
In File > Options > Add-ins
At the bottom, change Manage to Disabled Items, click Go
If you see "Microsoft Teams Meeting Add-in", select it and click Enable
Restart Outlook