1) Download the Resident Evil 7 Teaser Demo: Beginning Hour file on PS Store.
2) Open the demo and from the main menu choose "Buy Resident Evil 7: Biohazard"
3) When the PS Store opens up, choose the third image, on the right, "Game Page" (I don't know if it's exactly that name in English)
4) Press on the "Choose Version" button
5) Choose the second version and press "Buy"
PS Store will see that you are a PS Plus subscriber and will give you a 100% discount.
Same working for The Last Guardian and Detroit : Become Human