The plugins I have linked contain their own setups for movement. They should include a function for Blueprints, and a Task for Behavior Trees. Unfortunately, I have never used most of them, so I cannot provide specifics.
Not sure if you have a direction already, but one method for flying AI can be done using various line or sphere traces to detect things around it. For example, a line trace 1000 units straight ahead could check to see if something is in the way of the flight path, and if there is a blocking hit, the ai could turn using an interpRotateTo node to steer away. Performing this check at a quick interval can give an illusion of turning naturally.