Can the game possibly get a multi part download? 12gb is a lot.
The zip file could be split to 1 GB files, download each separately and then join them back to one large zip file. This might be too complicated for typical users.
I would rather spend time figuring out what is wrong with the downloads, I have not seen problems. The file does take time to download, but eventually it has arrived and no errors.
Seems download problems are somewhat common, so it might make sense to make it better. But I think I have not seen any user helped with download problems reporting back so it would be known what the problem was and how it was resolved. Or if the download just does not work no matter what.