The maximum number of free accounts has been activated on this iPhone

"The maximum number of free accounts have been activated on this iPhone" message is discussed in the support document "If you see a Could Not Create Apple ID or Could Not Set Up iCloud message." Click on this link --> https://support.apple.com/HT210743

This message generally "means that you have exceeded the number of new Apple IDs you can set up with iCloud on a single device in one year." See the recommendation in the link on alternative methods for setting up iCloud accounts, e.g. on a computer.