Disappearing Songs

I am using an iphone 11. I purchased an album, played it, fine. The next day half of the songs were missing. I tried searching in my library, my purchases, albums; checking for any downloads; checking hidden songs--to no avail. Sometimes all the songs are there, then on other days they're gone. When only half the songs are there, at the bottom of the screen it says "download complete album." So I hit that. It lists all the songs, but when I try to play them, they stop after a minute sample and then take me to the page where I can subscribe to Apple music. I don't want to subscribe to Apple Music. There seems to be no rhyme or reason as to when and how the missing songs appear or disappear.