How to persuade the school to let us contract the auditorium to show movies?

That's a good idea. You can apply to the school through clubs or student organizations. You can consult your counselor first and then make a visit plan. During the visit, let the school realize that this is a multi-benefit plan. Draft an application to explain how to operate it, such as printing simple movie tickets, managing orders, distributing benefits, etc. Colleagues can also give poor students the opportunity to sell snacks at the door. Then as for the relevant laws, you'd better pay attention to them again. Ordinary schools don't embarrass you. Good luck.