So that you can view the classes you are enrolled in as a student alongside the classes you've created as an instructor, you must be using the same email address for both roles.
Submitting on behalf of a student is only available via the desktop version of Turnitin. Paper submissions via the Feedback Studio for iOS app can only be made by students themselves.
If you're an instructor an a student in the same class...
...we will show only the instructor view in this instance, as we can only support one user type per individual class. In order to access the student view of this class, you must access the desktop version of Turnitin.