Hiya! Is the browser version or native version giving you issues? Here's a few things I can think of that might be causing that:
(Web) Make sure JS is enabled; You can use ctrl+F5 to hard refresh the page. If other instances of web Decker are loading for you, try opening the patternshop-cinnamon.deck to see if it still gives you a black screen?
(Native) When you launch the .deck file, it might be trying to use an outdated version of Decker, or your operating system cannot find an instance of Decker at all. (This happens to me on Debian all the time ;_;)