I have the same problem with an iPod Touch 5th generation, trying to download a pre-ordered Kids Bop 25. After an hour of trying various suggestions, I finally went to my account, canceled the pre-order, and bought it again. iTunes seemed very confused, because the pre-order had allowed me to download some of the songs available earlier, then would never download the rest. When I tried to buy it again, it offered me a discount on the album, because I already had some of the individual songs. That didn't work either. I finally just bought the whole thing over again, for full price, which means I ended up buying the whole album PLUS three of the individual songs on the album. Very, very annoying.