Despite enabling browser permissions on Chrome or Firefox to access your camera and microphone, Apple's Mac environment sometimes overrides this with extra permission settings. Follow these steps to make sure Lessonspace can access your AV on your iMac/Macbook:

First, click the Apple logo on the top left corner > Select System Preferences... from the menu. Then click Security & Privacy.

Click the Privacy tab.

Click Camera in the left-hand column, then tick the box next to Google Chrome. Do the same thing with the Microphone option. 

A small window will pop up, click Quit Now. By doing so you are allowing Google Chrome to access your camera.

If you don't see the Camera, Microphone or Google Chrome option, please update your macOS to the latest version (Click Apple Icon > About This Mac > Software Update...) and update your Chrome browser to the latest version (at the top right of Chrome, click three vertical dots > Update Google Chrome).