When you are visiting or using a website that wants to use your Webcam or Microphone in Google Chrome, you will have to grant it permission, otherwise the website or tool can't use them. The first time you visit the website it should show you a pop up that looks like this.
Click on the "Allow while visiting the site" to make sure that the tool has permissions to use your Webcam/Microphone.
If you missed that pop up or need to change the settings, you can adjust your browser settings by clicking on the settings option next to the URL bar and selecting "Site settings."
That will open up a settings tab with the options for the website you were on. (Each website has it's own unique set of permissions, so even if you've granted one website access to your Camera/Microphone, you may need to grant access to other websites/tools.)
Change the Permission from "Ask" to "Allow" to make sure this tool will always have access to your webcam/microphone.
Once making the change you can go back to the website you were trying to access and refresh (or click on the "Reload" button).
That website or tool should now have access to your webcam. The icon at the top left will change to reflect that your webcam/microphone are in use.
If your option for Camera is greyed out, you may need to adjust your computer's Privacy settings for the camera.
Clicking the "System settings" button should take you to the relevant Windows setting. (Windows Settings > Privacy > Camera)
Make sure "Allow apps to access your camera" is set to on. You might also want to scroll down and make sure "Allow desktop apps to access your camera" is not turned off as well.
Make sure both are set to "On."
You should then be able to go back to Google Chrome and allow website permissions for the webcam.