Ring doorbell works but existing doorbell does not

Hello, Just wondering why I cannot get my existing doorbell to work with Ring doorbell wired camera. The doorbell I have is the CHM1 and I cannot get it to work, I’ve read these instructions Your Ring doorbell won’t ring if the settings on the app are wrong. Follow the steps to enable proper settings: * Open the app and select your doorbell. * Press Device Settings. * Go to General Settings. * Select your ‘Doorbell Chime Type’. * You will see a dropdown menu. From that, pick ‘Mechanical’. * Turn on ‘Ring My In-Home Doorbell’ and you are done! If none of the above can’t get it ringing, you may need to reset the power. Remove the battery from the doorbell or flip the breaker to force it to restart. Forcing to restart this way should resolve the mechanical chime issues. However the “doorbell chime type” option is not available in the setting. Anyone got a solution? Thanks in advance,