Hey Matt,
my first guess would be that it has to do with java heap sizes - according to this post you’ll need about twice the pbf file-size in RAM per profile.
By default, you’re building 9 profiles (see the ors.services.routing.profiles.active-list in your app.config). That would mean you’d need about 5-6 GB of ram.
Have you tried setting up using the included heidelberg.osm.gz-file? That one should probably run even with low RAM. Other than that, if you don’t need all active profiles, you can remove them from the active-list and try with that.
Note, that it is entirely possible that I’m completely on the wrong track with this, so this is merely a collection of ideas for debugging 
Best regards