The link above when this thread was originally created is to the Plugin Pile which contains the latest version of Sorting Plugin. What you found was the archived version of the old project which states to go to the Plugin Pile for the latest version. The latest version of the Plugin Pile is 1.7.1 and when you get the correct version it should work for you.
GitHub link: https://github.com/foohyfooh/PKHeXPluginPile