While RailsInstaller hopefully mitigates a lot of the early pain of installation, it's inevitable that people will run into problems of gems that aren't Windows-compatible. It's just a sub-par experience for working in Rails. Thoughts about advising them to set up Ubuntu in Virtualbox instead?
The App Store no longer allows you to download XCode if your version of OS is less than 10.11. You can download them without the App store by signing in here : https://developer.apple.com/downloads/ and searching for Command Line Tools or Xcode
Upon selecting version 10.13 via leads to the congratulations page immediately. Not sure this is due to a guide not being written for 10.13 yet or a mis-redirection of links.
I am not sure if there is supposed to be the confetti animation as shown on OMR screencast but it doesn't show up on two macbooks both with chrome both on mavericks one retina and one not.