Should I replace my doorbell chime transformer?

I bought and installed a Ring Doorbell Wired (the black one). I bypassed the existing chime, that uses an UK RDL M412 transformer (8-24V). When configuring the camera, it fails by saying something like "Your transformer does not have enough power, please replace with a 16-24", however the specs said it should work with 8-24. Am I doing something wrong? Do I have to buy a new transformer? Which one? Can I replace it myself or do I need professional services? Thanks!