To get up and running, assuming you've got the correct Ruby installed (see the .ruby-version file), and a valid database.yml, should be as simple as bundle install && rails db:setup.
To run the test suite, rails test is your friend.
The site doesn't have any serious complications; there is no email, no background tier, and no other dependencies like a search service.
The app is hosted by Heroku and served from drinks.mixologi.st.
The domain is registered with nic.st. CloudFlare lives in front of the app, and provides both the name servers and the DNS service since it does a much better job than nic.st.