Starting with the newer versions of macOS operating system, security and privacy protections have been increased. Whenever an application needs access to the hardware components of your computer (ex. camera and microphone) a notification will pop-up asking for permission. If these permissions are denied, the application may not function as intended. 

Sometimes, the Chrome web browser may not have the necessary permissions to access the camera and microphone. This will prevent you from participating in Google Meet virtual meeting sessions. There is a way to reset Chrome to have it request permission to access your computer's hardware. 

Let's start with the Camera settings. Open up Chrome. Then copy & paste the following address into the address bar: chrome://settings/content/camera

• On this page you'll see the permissions for using the Camera in Chrome. 
• Under "Default behavior" make sure Sites can ask to use your camera is enabled. 
• Next, look for the "Not allowed to use your camera" section. 
  • If there are any sites listed in this section click on the trash can icon to remove them. 
• Under the "Allowed to use your camera" section look to see if https://meet.google.com:443 is listed. 
  • If so, go ahead and click on the trash can icon to remove the site.

For the Microphone settings go to chrome://settings/content/microphone. Repeat the steps above for the Microphone settings to force Chrome to re-ask for the permission to use the Microphone.

Go to the https://meet.google.com/ website and create a New Meeting. Choose the option to start an instant meeting. This should force Chrome to re-ask for permission to use the Camera and Microphone.