All it would add is a menu with folder links, similar to what Gnome 2 used to have. Likely, it will only open the folders in Thunar, that's why it wants to install it. It wouldn't put the icon on your panel that you're looking for.
Honestly, I'm a bit shocked the plugin you're looking for isn't available in the repositories. Granted, not too shocked as we're talking about Canonical here, but Ubuntu does have an official XFCE spin.