Although built with Meteor, I have used the build command with Meteor, so conceptually, it is just a Node.js application that will run behind NGINX. I'm new to web development (and computing in general), so I am looking for some help getting the app running. ... This should be a relatively quick job, as I suspect the issue is just some mistake in the port and URL settings for either Node or NGINX.
This apps runs inside google's compute engine, but as far as you're concerned, it should be no different than an Ubuntu server except for the firewall configuration (which I understand how to change).
... You would need understand how to actually deploy Node apps to a virtual machine and probably a good understanding of configuring NGINX.