Missing Purchases?

I downloaded the entire LANY by LANY album awhile back, but when I went to go listen today I only had 8 of the 16 songs on that album. A little pop up at the bottom said something like “see full album” so I clicked on it and tried to play one of the missing songs and it took me to and apple music ad. I first removed the downloads, and then I removed the 8 songs from my library. When I go into purchases in the iTunes store, it is not there. When I go through settings to see my purchase history, it is there. All of the songs are on my iPad, but I can not re-download them into my iPhone even though I know I have payed for the entire album.