Questions about Audio Blueprints

I’ve watched and set up my BP ambience just like he did in this video (I followed it step by step):

But I’m not sure what type of triggers he’s using for his “boxes” in the actual level. I’ve tried setting this up using box triggers and volume triggers on “begin overlap”, then using a remote event to use this ambience BP but it’s not firing and the ambience isn’t heard. Also, we spawn in already inside the box to the first ambient zone, and box triggers and volume triggers don’t have “auto activate”. Can someone help me out with this? When I spawn in the ambience isn’t heard, even if I travel outside then back inside the box (or volume) trigger.

Also, what logic is he using for the “are you inside or are you outside of the box”? He’s using a custom event called “Exit_AmbientBox” but what is the logic behind checking to see if the pawn/player is inside or outside the box?

Thanks,