Perhaps a .rar package(s) can be included alongside the .zip, perhaps for those with weaker connections. When I tried to download the XR vessels for the first time, the download would cut out before it completed, leading to a corrupt file- downloading the .rar fragments worked a charm.
Though to prevent the aformentioned "HAO DO I OPEN TEH FILEZ" questions, perhaps a clear explanation should be given about the benefits of downloading the .zip.