He has a tour bundle, which helped a lot. Mind you, none of the singles he's released were hits Let's compare this album's first week sales to his peers:
Zayn's last album:
Camila (includes tour bundle, multiple album covers, discounted album during the first week, etc)
Liam's new album released last week (universally panned)
Source: link link link link
How do you explain Harry's success? Gay pandering? White mediocrity? Talent?