The Issue:
You do not have the icon to add Teams connectivity to your Outlook appointments (see below).

The Solution:
1. Open the Teams Client application

• Start > Type the word Teams > Press enter

2. Click your profile picture in the upper right corner
3. Click the button: Check for Updates

Look close for Messages in Teams

Note: Teams will display a few messages to you to let you know when the updates are complete.

4. Close Outlook
5. Reopen Outlook
6. Create a new appointment and the Teams connectivity button will be there. …. </Boom>

A full computer reboot may be needed if you have not installed windows updates in a while.