Is it permissible to download reading materials onto the school tablet, circumventing the Ministry’s restrictions, knowing that it will become the user's property after graduation, and that the materials will be erased before exams?

As long as the Ministry prohibits downloading books onto the student's personal device, then it is not permissible to use trickery to download the books onto it, even if the student intends to remove these books from the device before the exam.