Need help (asap)

Hi, i need help with a gamecube iso i downloaded. i downloaded super mario sunshine ISO from a website that i found on google and it took me a whole day to download it (overnight too) and when it finally downloaded i tried opening it and it opened with winzip and inside the file i saw another winzip file that was the same. so i opened that one too with winzip, and when winzip opened it said
Error: internal error processing iso image.
and from there i dont know what the hell im aspose to do? can someone help me i really need this to work (im doing this for a friend)