Preordered album error messgae

I preordered Magic Man's album Before the Waves a few month ago, and it came out last week. The first day the album was available I went to download it, but it told me I had to pay to complete my album (the "buy album" button didn't say "purchased" or anything, just "complete my album"). So I pressed the button, typed in my password, and I got an error message saying "This item is being modified. Please try again later." I have tried to complete the album once a day since then but it has not worked. I was, however, able to buy an individual song off of the album. Is there a way to get this album without paying for it again?