u/COMBO-Fantasy-Sports

I vibe coded a functional MVP website for my Fantasy Sports company that combines multiple sports into a single league with multi-sport drafts, cross-sport trades, and year-long sh*t talk.

The website works, live data is integrated, the multi-sport mock drafts run smoothly. But I know I need to clean up my security and authentication process. I will eventually charge a yearly subscription to play, as a SaaS business model. What is best practice to use vendors for authentication, for payment, and even for simple online banking?

AI (Lovable) will recommend outside vendors, I just want to make sure I build this correctly. Any help would he greatly appreciated!!!