This is not an addon itself, but rather, art made by Septula for the AddOn KgPanels.
YOU MUST HAVE KGPANELS INSTALLED BEFORE USING ANY KIND OF KGPANEL ART.
If you are unfamiliar with KgPanels, it is an addon that allows you to customize your UI. Inside of this download is a READ ME that includes instructions on how to install Kg Panel Art, not Kg Panels itself.