Do you have Swan Lake in iTunes/Music on any device and is that device and your iPhone both signed into your Apple ID? A tune does not have to be downloaded to a device in order for it to be played on that device. It can be streamed as long as you have a WiFi connection or have cellular data activated for the Music app.
If you are streaming a tune in Music a touch in the wrong (right?) place can immediately add that tune to your Music Library and/or cause it to download.
If you have an Apple Music membership you do not even have to have a given tune in your Library to play it much less have it on the particular device.
Last edited by joemikeb; 10/09/19 05:48 PM.