Okay the one you have linked is actually to make the buffs in a list on the left and right side of the screen, that is the default for nUI so erase it get it out of there that's why you are getting an error. To get the buffs to show up as only icons along the bottom of the screen you must download and install
http://www.wowinterface.com/download...raButtons.html as far as size goes can't do that without editing the code for now but the author is working on a full gui for everything
edit: If your looking for the buffs to be in list form then just use stock nUI without any plug-ins for the auras (same thing goes for the size)