If you want to run the slides project yourself, you'll need a copy of the Java 8 SDK and Leinengen on your computer. How you get those is up to you. Once you have them, you can run:
lein run -m clojure.main script/figwheel.clj
Which will boot up the figwheel app and drop you into a repl. You can now page through the slides at http://localhost:3449. Any changes you make to the clojurescript or scss files will be hot-reloaded.
The deck was built with the Cursive plugin for IntelliJ Idea. If you want to use that environment, you can download Cursive and set up a new run target using these instructions on the Figwheel wiki. This will provide a somewhat better development experience.