Bought a house with a Ring Video Doorbell - how do I set it up?

I just moved into a house with a Ring Doorbell. I have no idea what model it is. The units are attached to the walls so I can’t access any QR codes, only a numerical code inside the faceplate but I can’t find anywhere in the app to input that. I also can’t find any info within the app regarding transferring Ring ownership. I just downloaded the app today, so I’m assuming it’s the most recent version. How to I get the doorbells set up and transferred to my ownership.