The UI skins have nothing to do with the plugin files that are needed to be downloaded from the first link you put up. Those files are only needed in order to use the plugins, which are not the same thing as the UI skins. If you are trying to use a plugin and download the necessary lotro files, try using Internet Explorer. I tested the link and it works just fine. For some reason firefox doesn't like it. lol So open this link
http://content.turbine.com/sites/lot..._LuaPlugins.7z
with internet explorer and it should work just fine. That is, if you are trying to use the plugins and not a UI skin.
~~Thay