Once you have the 2 files downloaded from eq2interface, most people (including Darq, the creator) say you can drop them into the Everquest2\Ui folder.
No need to run as Admin, in-fact Darq even says in a video that it is better not to run as Admin. The DarqUi Unified app (light blue) is the one that updates.
It should ask to install everything for you.
