Mac OS requires privacy settings to be enabled for the Microphone, Camera, Accessibility and Screen Recording/Sharing. Certain apps such as Teams, Zoom and Collaborate need to be enabled in System Preferences to use these features. 

Click the Apple icon on the upper left hand corner of your Mac to access System Preferences. Select Security & Privacy.

 On the Privacy tab, select Screen Recording and check the box next to Microsoft Teams (or Zoom). Repeat these steps for Microphone, Camera and Accessibility.

NOTE - You may need to click the lock on the bottom left to enable changes.