Best way to set up client portal with 2fa?

Basically we just want client “portals” where they can log in and upload/download files and we can do the same. Obviously the admin account would have access to all files and folders and each user would have access to his individual shared folder/portal. I installed Apps Guests and Two-Factor TOTP Provider. What procedure should I use to set this up? I also set up smtp with an smtp provider to send out email invites.

I think it does not work. I think you need normal users. You can configure them with 0 Bytes and give them access read/write for e.g. group folders. Thats similar to guests.