Hotspot Centralized Authentication

Hello guys, I am attaching a simple diagram to what I would like to be able to do. The question is simple:

Which routerboard model should I use in this setup?
Clients.jpg

Any with a license level 4. A 750G should be able to handle 40 clients that only log in occasionally just fine, a 450G could definitely do it, anything above can, too.

Thank you fewi, +karma to you