Well, as far as i remember, in Evo you get 2 types of users: web users (front-end) & manager users (back).
That’s no more the case in Revo, users get rights for front &/or back.
Anyway, you could either create a user with only front-end access (to the required context(s)), set a login form… but as you asked for a "quick" way, i didn’t mention that
Good luck!