If you’re on Mac, try the steps at https://farplay.io/tipsandtricks/#camerapermissions for giving FarPlay permission to access your camera.
If you’re on Windows, try the steps Microsoft provides at https://support.microsoft.com/en-us/windows/manage-app-permissions-for-your-camera-in-windows-87ebc757-1f87-7bbf-84b5-0686afb6ca6b. Try disabling security software like Norton.