Yes. You spawn an actor from class and assign it to a variable. Or drag the blueprint to the level blueprint to reference it there. And another way to instantiate is to use a Child Actor
Perhaps you could briefly describe the role of this manager, this way we can try to give you a more tangible suggestion.
Perhaps this manager can be created and referenced by one of the framework classes (pawn / game mode / controller). These are easilly accessible with global getters by any blueprint.