This exactly. MS will confirm your eligibility for the Sorcerer AP, and you’ll complete the purchase over the phone. The nice thing about the new process is that your renewal will activate automatically on the relevant date, and you won’t have to stop at GR before you use it the first time.
You can renew in person at GR outside or inside the parks or at DS, as long as you have photo ID and DVC Y showing in MagicMobile on your phone.
ETA I think you can renew at any ticket booth, too, with ID and DVC Y.