I had the exact same thing happen to me: FTP in zwift was 212 - ramp test in TR (when I was just starting my structure training journey) was 189. It was a little demoralizing but I took the 189 and the subsequent workouts were plenty hard. I’ve “made that all back” (in quotes as who knows the “true” value due to differences in methodologies and such) and then some while on structured training.
With AT, I think that either way you go though the adaptations should keep you covered.