In the present, the world is in mourning over Superman, whose death triggers the Mother Boxes to reactivate and Steppenwolf's return to Earth in an effort to regain favor with his master, Darkseid.
The world is in mourning over Superman. This is in the present. Superman's death triggers the Mother Boxes to reactivate in an effort to regain favor with his master. Superman's death triggers Steppenwolf's return to Earth in an effort to regain favor with his master. Darkseid is his master.