TutuApp is a hack to steal for-fee apps. It is not supported and you won’t get help with it here. Apple does not support illegal side loaded apps. By installing such apps and trusting their profile, you also open your device to possible malicious software installs without your knowledge.
There is one, and only one supported source for iOS apps and that is the Apple App Store. And the only way to legally and legitimately get, install and use for-fee apps is to pay for them.