When it comes to saying that there is a plugin, it is to be assumed that there has to be a user of that plugin. Since you are a PhpStorm lover, you can safely assume that PhpStorm can be (one of the) possible users of the plugin. So, you need to act as a pseudo recipient of the library plugin and make an attempt to use the library. By configuring, it is to be understood as making the necessary adjustments in the project structure so that the library can be used to add functionality to the project. The age-old practice of reusability is at work, you see.
The main advantage that is associated with a library plugin is the ease of inclusion in a project. You just have to make use of this advantage.