I won't walk you through the build process again. But I would remind you to make sure that you have the Chapter 5 scene added to your Scenes in Build list.
Alright, once everything is built, compiled, and deployed, load it up on your HoloLens and walk around. You should hear the various collections of sounds getting louder as you move from one area to the other.
One experiment you might want to try, especially if you are working with limited space, is to change the positions of the Audio Sources from a 2-meter square to a 1-meter square.