Write to saifsiddiqui2409@gmail.com. A person reads it.
Two things have to be true. Tread needs Screen Time access, which iOS asks for once and which you can check in Settings, and you need to have picked at least one app under Blocking. Until both are done there is nothing for iOS to put a shield in front of.
The price is built from your own seven day average, so it moves as your average does, and it is different at 10am than at 10pm because being ahead of your usual pace by mid morning is what makes minutes cheap. Progress shows the baseline the price is using. If that number looks wrong, Health is the place to check first.
Tread reads Apple Health if you allow it, and falls back to the phone's own step counter if you do not. Health sees an Apple Watch and other apps; the phone counter only sees what the phone itself carried. If the two disagree, Tread takes the larger.
Invite codes are six characters and case does not matter. If a code is refused, check it against the one the other person is looking at under Progress: it is shown in full there.
Open Profile, then Club, then Restore purchases. Club follows your Apple ID rather than the install, so a new phone gets it back.
Profile, then Delete account. It removes everything from the server and wipes the local data, immediately, and it cannot be undone. Deleting the app on its own does not do this, because the account is deliberately built to outlive the app being deleted.
iPhone on iOS 17 or later. Tread uses Apple's Screen Time APIs, which iPad and Mac do not offer in the same way, so it is iPhone only for now.