Occasional official giveaways sometimes provide free character avatars or small digital bonuses rather than the full game. Go to product viewer dialog for this item. Resident Evil 5 - Sony PlayStation 4 [Digital Download]
Second-hand physical copies for PS4 can be found on sites like Amazon or GameStop , often at lower prices than digital retail.
In conclusion, while I understand the desire to access free content, I encourage you to consider purchasing the game or exploring legitimate free alternatives.
You cannot simply download a free PKG file onto a standard USB drive and play it on a normal PS4.