How do I get passenger to serve my page on port 80 or 443?

I followed the guides (starting here: https://linode.com/docs/development/ror/ruby-on-rails-nginx-debian/) to setup my server for RoR on nginx and debian, using Passenger. However, I can only load my site on port 3000. The closest I can get to accessing my site without specifying the port is an error page from Passenger.

I'm happy to provide information on my server configuration.

For starters, here is my /etc/nginx/sites-available/[mysite] configuration.

server {
  listen 80 default_server;
  listen [::]:80;
  server_name 45.79.8.49 vault.ifrog.com;
  passenger_ruby /usr/local/rvm/gems/ruby-2.5.1/wrappers/ruby;
  passenger_enabled on;
  root /var/www/html/vault/public;
}