Why don't I see "iTunes Store" in upper right corner when searching / attempting to buy a song without a apple music subscription?

If iTunes Store doesn't show as an option at the top right of the Music app on a Mac after you click in the Search box in the sidebar, see the following from Buy music from the iTunes Store - Apple Support

1. Open the Apple Music app.
2. In the menu bar, choose Music > Preferences.
3. Go to the General tab, select iTunes Store, then click Ok.

If there are not options at the top right of the window after clicking in the Search bar in the sidebar, go to the View menu and see if "Hide Lyrics" or "Hide Playing Next" are displayed rather than "Show Lyrics" or "Show Playing Next."

If none of the above help, see if there is a very small < near the top left corner of the main window in Music (to the right of the Search box in the sidebar). If there is, click the <.