Q: Is iTunes compatible with Digital Copies?

I recently bought Iron Man 3 on DVD and it came with a redeemable digital copy code. I went onto my iPhone to download it, and the only way I could see how to was through iTunes, using digitalcopyplus.com on safari. When I tried this, it was unsuccessful. I'm still currently trying to figure out how to download it on my own, but I am having no luck so far and was hoping somebody would be able to assist me.