Generic vs AI version of Events in Behaviour Tree Task

Thank you very much.
My thinking is stuck in this: If AIOwner is the Controller and I don’t want to provide one, since my Actor is not a Pawn, how do I use a Behaviour Tree in blueprints without specifying a Controller?
I tried to provide a null Controller to the blueprint node “RunBehaviourTree” but this gives a runtime error.
I also checked out the blueprint node “SpawnAIFromClass” but this also expects a Pawn.

Thanks