I agree with terlin, and I also had a few concerns about the plugin.
1. The last released version was on May 5th 2018 for 1.12, so it is most likely broken in 1.13 and wouldn’t work with the server.
2. The original developer has ceased working on it, and a cursory scan of the GitHub shows that almost no one else has contributed since. In other words, we can’t reliably assume that bugs will be fixed well, ever.
3. It was difficult for me to understand what exactly this plugin does at first, but it looks like it adds custom items? A bunch of the custom items that the plugin wiki listed, would duplicate existing donor perks. Obviously we would have to disable those. It got too complicated for me, after looking at the medicines and weapons custom items, but I will give it another look. I am also concerned about how much these custom items would change the gameplay of the server.
In conclusion, I am worried this plugin would require a lot of effort, time, and technical skill to setup and maintain, for questionable benefit to Sentinelcraft.