Search field for iTunes Store

There should be a search field at the very top of the left panel, above the Apple Music section, that is the general search for Apple Music, your own library and the iTunes Store. You may need to scroll up to see it.

Enter your search there, then select the iTunes Store tab from the results on the right.

If you don't see the result tabs at the top right, click on the < arrow to return to the main results screen. You may need to click it more than once to get the tabs to show up.

Correct. The scrollbar is not always visible.

Try this: go to Music -> Music Preferences -> tap General -> check Show iTunes Store -> OK.

Another check -> go to Music -> Music Preferences -> tap Restrictions -> uncheck iTunes Store. 

note: The host will remove your screenshot contains private data.

OP screenshot.

Here an iTunes Store search field (top left), also a lot of playlist, and it is possible to scroll down.

It's probably just scrolled out of view. They seem to have a lot of playlists, which may cause the panel to scroll.

Thanks!! That "<" button was the far-from-obvious solution to a problem that's been driving me nuts. You're the first person who's pointed it out!

You're welcome. Glad it worked out.