Time to record some vocals?
The first time you add a Voice & microphones track, you will be asked to allow microphone access (1). Once allowed, you should see that you have input activity in the small purple bar next to your input device name (2).
For more information on how to change your input device and channel, check out this article.
Good luck :)
(1) Allow microphone access (this is how it looks in Chrome)
(2) Input activity in the input device selection