Sometimes The Unify Challenge platform doesn't have access to your computer's correct mic or camera.
To allow access to your mic and camera, please first click the three dots next to the Mute button in the lower left corner of your browser window
Click "Audio/Video Settings"
Verify that the correct mic and camera are selected
If you need to make any changes to the selected mic or camera, click the "X" in the top right when you're done