EA kind of hacked the patch to enable XML modding. Due to this, there are a few install steps apart from the standard "drop the package in your Mods folder":
1 Unzip the package file to your Mods folder as usual.
2 The following two steps are required if you haven't already done them...
3 You will need to create an empty sub-folder in your Mods folder called unpackedmod. (Don't put the package in here, you can keep this folder empty)
4 You will also need to edit your resource.cfg file in the Mod folder. Add a new line to the end with the following text: DirectoryFiles unpackedmod autoupdate