For some reason you can get it, then you couldn’t, but now you can (except for Europe). It was originally announced that Psycho-Pass: Mandatory Happiness will be available as a cross-buy for the PS4 and Vita for PS+ subscribers in North America. However, when release day came, users were unable to download the title on the PS4. Apparently the game wasn’t supposed to be a cross-buy but thankfully NA PSN made it free for the PS4 as well shortly after the incident.
All is not well on another side of the world as PS+ subscribers in Europe aren’t able to get the game for the PS4 as it remains only for the Vita at least for now.