The AU is the Auto Updater (patcher program that updates the ThorUI files when Faetyl releases any newer versions), which you probably downloaded from
http://eq2interface.com/downloads/fileinfo.php?id=3859.
If you didn't get this (still dealing with a pre-AU version of ThorUI, I highly recommend you delete your current ThorUI folder and install this updater program....as any older versions are most likely not supported anymore (since being replaced by the AU).