This doesn't add up for me.
The character data in the main download for Modern Interiors is only 83MB(including the "old" folder) so unless the generator has over 156 times as many options, it has no right being 13GB.
I also get the header error when using 7zip.
Also, something odd, the download is only 147MB, but it expands to 13GB when unzipped? That seems seriously off. Most of the data has to be empty, or trash.