The forums show unresolved issues with this plugin. Still, I tried it. Only to find it doesn't work.
I installed YOURLS on a new domain. It was up and running without problems. Then I installed this plugin and found it only generates short URLS for new posts. I have thousands of old posts. The only option I could find to resolve that was to edit each post and save it. And that suggestion was by a plugin user, not the author (who had ignored those forum posts for months).
Since I had no intention of editing that many posts just to get YOURLS short URLs generated for each one, I removed the plugin, removed YOURLS, and installed JetPack instead--which generated wp.me short URLs without incident and for new and old posts.