I need to but cannot purchase DRM-free version of a song through iTunes

I currently have an Apple Music subscription and have downloaded the DRM-free version of a little over 300 songs. I've created several playlists that contain a combination of Apple Music songs and songs I've purchased through the iTunes store. I'm cancelling my Apple Music subscription soon, therefore I need to actually purchase all of the Apple Music songs I have downloaded so I don't lose access to them. When I search for the song in the iTunes store, it does not provide me with the option to purchase the song, only play it. What steps do I need to take to purchase these songs? I need to cancel my Apple Music subscription soon and need to take action ASAP. A quick response is much appreciated!