To run an Xcode project on an iPhone/iPad without paying US$99 for Apple Developer account, this error message may happen:
Your development team has reached maximum number of registered iPhone devices.
According to StackOverflow, I got this warning because I have a previous paid account but I cannot configure it at this stage. So I register a new and free Apple Developer account. and add it to Xcode with Preferences->Accounts.
The project with Xcode 11.6 is configured as below:
After selecting the new Apple Developer account as the team and making sure that the bundle identifier is new, the deployment becomes successful!