If you are trying to join a Teams meeting and can't get your camera, microphone, or screen sharing working from you laptop you may need to allow MS Teams access to your Camera, Microphone, and Screen Sharing. 

1. Quit Teams, then reopen it.
2. Next, open System Preferences/System Settings by clicking the Apple icon in the top-left corner of your screen and then choosing System Preferences/Settings.
3. Next click on Security & Privacy
4. Scroll down to Microphone. Here you want to make sure Microsoft Teams is checked.
5. Repeat step 4, but this time click on Camera.
6. Repeat step 5, but this time click on Screen Recording
7. You may need to restart the Team app again at this point.
8. Quit the MS Teams app and open it again.

Note: If you do not see Teams listed in the Microphone, Camera, Or Screen Recording areas, it means that Teams hasn't prompted you to allow that specific access yet. The next time you try to perform a Microphone, Camera, Or Screen Recording function in the Teams app, it should prompt you to allow the requested access.