Q: Preorder won't download

I ordered the preorder for Oh, What a Life sometime in January. The album came out six days ago. I've been trying to download it on my iPod for the past few days, but in iTunes on my iPod it says purchased, like it did when I ordered the album. Why won't it let me download it? I don't have a balance on my account so is that what's causing it? Is there anyway I can download it without getting on my computer?