Actbusy Queues are a superset of the Actbusy system. They're less useful than the base Actbusy system, having been created to solve a single specific problem: making a queue of NPCs. If you're trying to do anything other than that in your map, it isn't what you're looking for.
An ai_goal_actbusy_queue tells a NPC to join a preset queue of actbusy hints. The NPC moves along the queue under the control of the goal.