Follow the link and press Update at the bottom: https://developer.apple.com/app-store-connect/submission-update/ . Then press "Enable". It's going to activate all new features for your account. All new features are going to be available by default after January 25, 2022.

It's quite simple: if it's a digital item (app, coin, music, book, video) = in-app purchase 30% commission. if it's a physical item (food, book, Blu-ray Disc, real life service - taxi, delivery) = Apple Pay / credit card, no commission.

iPhone 6 / 6s / 7 / 8 Plus: Point resolution (UIScreen.main.bounds.size): 414x736 Theoretical pixel resolution based on @3x scale (UIScreen.main.nativeBounds.size): 1242x2208 === iPhone Plus has a physical screen 1080x1920, so: UIScreen.main.nativeScale is supposed to be ~"2.60869565", but the simulator still shows it as "3.0", maybe on a real device it's different. UIScreen.main.nativeBounds.size is also supposed to be 1080x1920, but on simulator it's not.

Select in Project navigator panel "QEMO-Manager" > Signing & Capabilities > Team > select your team / developer account. Select in Project navigator panel "GitHubUpdates" > Signing & Capabilities > Team > select your team / developer account.