the only thing that matters when uploading a world is if you're uploading the world folder
i'm not entirely sure if this is what works, because i'm taking this information from another user, but you could try right clicking where it says 'download' on your mediafire link, and then copying it and using that instead
here's an example for the download link
http://download1109.mediafire.com/0boufvnd27bg/i6hxcuho0c7cqho/TANTALUS+PvP+pack+-+v1.4.zip