Choosing the right stack for my webapp

Hello fellow indie hackers.
I am an Applied Math university student with an idea that I want to develop.
Basically I want to create a subscription based webapp that lets user prepare for medical school admission exams here in Italy.
The web-app would include PDFs of the theory, video lessons, tons of exercises and exams simulations. I feel there is space for this because the only options are:

1. prepare by yourself buying 100/150€ of books
2. Buy expensive local coursers for about 2500/3000€ for ~120 hours worth of content.

Now onto my question. I am currently building the frontend with Bootstrap.
But I am unsure about the backend, probably Django?

I will integrate the payments with Stripe/Paypal and let user login with OAuth so that I do not store any sensitive data at all.

I am bit unsure how I will be saving what kind of subscription the user has, but maybe stripe already handles that?

I am just open about your opinions on this. Any tips is accepted! If you also have some resources that you want to share on how to learn how to do this I would be grateful! I know how to code but I only focused on Advanced mathy algorithms <_<