I took a look at the scripts and nodes and I see that the issue is that you didn't change the volume multiplier on the main speaker node. Also, it does not loop properly because you didn't set the intro as a seperate soundnode wave. If you'd like for me to fix these things for you, I can send you the files since I am already fixing it in my own game :)

The way to setup the intro + looping is described in this guide:
https://steamcommunity.com/sharedfiles/filedetails/?id=1290866659

One of my favorite remix mods, but can you please turn the volume down? It's way too loud. Louder than the original spaceship theme is fine because it sounds more epic in general, but definitely not this loud. I had to take a break from it for a while, even though I love it.