OK I found what the problem is : actually, after decompression, the files ARE in the folder. But the files names start with a dot, which makes those files invisible on most operating systems. Not very smart… So you have to use an app that can "see" invisible files and simply rename those files, removing the dot. For instance FTP apps can do that. Some other free utilities apps can do that, at least on a mac. I hope this will help.