shinyproxy basic basics (+ some general web knowledge)

The problem

While searching for ways to deploy shiny apps I stumbled across ShinyProxy. From what I understand it's an alternative for ShinyServer. However, I lack some (very basic) knowledge to follow the guide provided.

The questions

1. Can ShinyProxy be installed just on any bought/rented server? Do I need to preinstall some other software?
2. Where do I type in the commands provided in the ShinyProxy guide?
3. Does Docker need to be installed on the server or is it a tool to deploy to the server and is thus installed locally?
4. The ShinyProxy guide misses a point about installing ShinyProxy. Why? Is it not installed (or is installation so obvious)?
5. I couldn't actually find instructions on how to run a shiny app with ShinyProxy.