Solution for a large amount of user logins [closed]

I’m looking to build a site for a friend but it has to support user logins (with custom roles) in the thousands and this is where I’m stuck.

I’m looking to make it a static site hosted on netlify and netlify has an identity service that lets you have 1000 user accounts with roles in the free version and a bit more but at a big price jump of $ 99/month.

I also looked at auth0 because it offers 7k user accounts for the free tier but no custom roles and in order to get custom roles you need to upgrade to the next tier which actually cuts down the amount of accounts you can have to 1k.

I’m not sure how else to handle this many user accounts without a hefty price. I could maybe host a database on a cheap server but I feel like costs might get out of control with that as well.