If a class A uses a method from another class B, you should model it as a Usage dependency from A to B depicted below
Now I am pretty sure that you mix two differents User.
When you said that you PortalController is able to manage a set of User, you are dealing with the structure/implementation of your system so it seems normal to have two classes.
When you said that a User logs to your system, you are dealing with the use case of your system. So in this case the User would be an actor using your system.
Does it help?