I think this is running the demo app that comes with the shiny package, not from shiny-server because shiny-server runs on port 3838 by default. Locally you would access it with local_ip:3838/appname and from remote locations with public_ip:3838/appname
It is located in this path /etc/shiny-server/shiny-server.conf
If you are interested I have a blog post that gives an example of how to expose your home shiny-server to the public internet.
The official instructions are pretty straightforward
Have in mind that you have to configure your virtual machine to have its own private IP and not share the host's IP so you can forward traffic to the virtual machine.