The copyright setting of a zApp or Book determines how it can be used outside of your institution but has no bearing on how much a zApp or Book can be altered and used within an institution.
Any zApp or Book taken from the sQuizya Library is free from copyright restrictions for personal or internal use. Copyrighted zApps and Books can be manipulated and assigned to any user within your institution, and individual questions can be imported into other work for personal or internal use.
However, no part of a copyrighted zApp or Book can ever be distributed outside of your institution. Even if just one question from a copyrighted zApp was imported into a new zApp, this zApp will never be able to be seen or used by anybody outside of your institution.