Database selection dilemma

I'm building a notes storage app (kind of like Google Classroom) for my college, where students can view notes, teachers can upload them, and there's an admin panel to manage everything. The frontend is in Next.js, but I’m still deciding on the backend.

I need something with free storage (since my college doesn’t wanna spend money) and supports user authentication & file management. I was thinking of Appwrite but using it locally from a college pc as a server and storing the data (notes files in this case) there. I DON'T KNOW HOW TO USE IT THO OR HOW IT'LL WORK.

I can't afford any paid plans T_T