Advice on how to build web application with existing frontend that needs authorization and payments

Need help
1

I’m building a web application that allows a user to translate 1 document for free and requires authorization and a paid subscription for more docs. I have the frontend that uses websockets to translate a document. I need to add authorization, accounting, paid subscriptions and connect everything together. What is the best way to do it using Bubble? And how much time will it take for a newbie? Thanks a lot!