In the Blizzard Desktop App playscreen, select the WoW icon on the left, then go to the version dropdown on the bottom and change your version to “Public Test Realm (Classic)”.
The Install button will then install what you need to play.
In the Blizzard Desktop App playscreen, select the WoW icon on the left, then go to the version dropdown on the bottom and change your version to “Public Test Realm (Classic)”.
The Install button will then install what you need to play.