Bought music won't download on phone or computer

I bought music way before I had apple music and now that I don't have apple music the bought music I had on my phone is there and it shows up in my purchases to let me download but not all of them when I search them through the music app to see if I have to rebuy them it shows up as purchased and so has the other songs that ive bought thats not on my phone or laptop. They show in my past purchases also when I go and look for them but it will not let me redownload them at all on my phone or computer, i also have the new IOS 12