Load all tracks in a playlist at once - Apple Music app on a mac
If you want to load all (iTunes Match) tracks in a playlist at once you need to switch to a different list view.
If you open a playlist you'll get a nice large list view. You can select multiple tracks but it is not possible to trigger the download for all these tracks.
But if you switch to the "show as title" view, you can trigger all at once:
Now you can select all tracks you want to load and select this menu item from the menu bar.