You must first setup the Yale Smart Video Doorbell. To introduce the Yale Doorbell Chime plug the Yale Doorbell Chime into a power outlet and press the middle 'speaker' button for 2 seconds until you hear a pairing sound. After that sound is played the Chime is in pairing mode, to then link your Yale Doorbell Chime to your Smart Video Doorbell press the doorbell button on the Yale Smart Video Doorbell, a sound will be played to confirm that the pairing is succesfull.
You can view the setup instructions in the Yale Home application, go to Settings for your Yale Smart Video Doorbell, under Utilities you will then find installation instructions for the Yale Doorbell Chime.