In the URL bar, find the video camera icon and click it. A dropdown modal will appear like this:
Make sure your camera and microphone are allowed for Konf.
You can also check to see if Konf has access to your Audio/Video devices this way:
On your computer, open Chrome.
At the top right, click More Settings.
Under "Privacy and security," click Site settings.
Under Site Settings, locate Camera and Microphone. Konf should be one of the approved sites.