The current version of the Vox Populi installer (v18.104.22.168) has a flaw. It installs the EUI mod in the "standard" Steam folder rather than where the game is actually installed, even when the Windows registry is correct. The solution is simple. Just move the folder UI_bc1 from Crogram Files (x86)\SteamApps\common\Sid Meier's Civilization V\Assets\DLC to its correct location, which is <wherever the game really is>\Assets\DLC. The symptom of this error is a failure to install 8 texture files. Actually, there is a warning in the installer that the registry must correctly point to the game folder. Obviously, that isn't the issue. Unless the developers want to fix their installer, at least they should note what I have written above so that others don't fall into this trap. I see on the web that many others have done so and seem to flail around trying to fix it, and the suggested solutions are completely off the mark.