Attaching a Controller to a Character

So just to start out, I am really new to Unreal.

Basically what I am trying to do is make a top-down game with AI. I am battling to figure out how to add a controller to an object. Obviously I created a template project (the top down project)
so I already have the TopDownCharacter blueprint to use as my player-controlled character. I have made a class that extends the “MyProjectPlayerController” in an attempt to write some AI
movement code in here (such as code to move AI along the NavMesh).

How would I go about setting my extended player controller (which has AI movement as opposed to human input movement) as the controller for various AI characters in the world?
Some C++ code would be much appreciated. (Kinda hoping for a Controller = CreateSubobject<MyAIController>() type of thing :P)