I’m building my first website, but I just encountered a problem that I have not been able to solve:

I have a python flask app as well as several HTML files that make up my website, hosted on a VPS

The problem is this: I want visitors of my website to be able to create accounts on my website and I just can’t make this work. The idea is to add billing later on for a “premium” plan

I have alrady tried several approaches, such as installing wordpress on my VPS (which didn’t work, but I would be ready to try this again if you think it’s the best idea) or installing wordpress on a webspace, but I gave up this idea because managing the communication between wordpress and my flask app, which has to be on the VPS (not webspace), would have become too complicated. Now I’m trying to create a user management system within flask, using SQLAlchemy and SQL Lite, but I fear that if I do everything on my own things will become too complicated later on, when adding billing

How can I make this work? One of the 3 methods I have tried, or another one?

I need users to be able to create accounts and I need to be able to charge them money. Keep in mind that all of this is running on a Ubuntu VPS and the main code is a Python Flask application