This is not about the content of WordPress, it's about the way you provide to download it. I assume you used the php function readfile() or something like it to associate the url with the latest .tar.gz or .zip file.
The problem is that your site doesn't seem to include the Accept-Range, nor accepts the Range header, and the download can only be done from the start to end.
My connexion is very bad, and it is sometimes broken after 400ko downloaded. And I must redo the download from start.