How to assign a user multiple roles?

Hello! I have been searching for a way to assign users multiple roles and can’t find an answer. Our users are grouped into either the “Client” role or the “Employee” role. We would like to gate content for certain clients, i.e. this page only Client A can see, not Client B. I thought I could create user roles for each client but they also need to keep the “Client” role.

https://docs.ultimatemember.com/article/1494-how-to-set-role-priority-for-user-roles

This article says “Users may have multiple roles,” but when I edit a user, the Role is a dropdown so you can only select one. The article says you assign roles with a priority, but it’s not clear how to assign a user two roles using that priority number, it’s very confusing to me.

How can I assign multiple user roles to a user? Thank you so much!