There's 2 reasons why you can't record: either Chrome settings are not properly set up, either Mac OS is preventing you from using the mic.
You'll find below fixes for both cases.
Step I - Allow the microphone in Chrome
That should solve everything.
If you still have problems, your operating system must be blocking the mic.
Follow the second step to fix this problem.
Step II - Allow the microphone in Mac OS
To check the box:
- click on the cadenas at the bottom left
- enter your password
- check the box next to Google Chrome
Now you should be good. Enjoy Teachee :)!