Allow Camera or Microphone
System Preferences > Security & Privacy
Select either Camera or Microphone on the left-hand side.
You’ll see the programs listed with check boxes that have access on the right.
To change the access, click the lock on the bottom, enter your computer’s password, and check the box next to the project to provide it access, then click save.
Note: You will likely need to restart RingCentral or Zoom to have the new system preferences kick-in.