Yes, even if you preloaded the Season 6 update on PS4, you still have to download and install an additional file in order to play Modern Warfare multiplayer. This is similar to the other multiplayer packs that have been released for the game.
Installation on PC (Steam) Launch the Steam app and log in to your account. Select Library. Find and select Call of Duty: Modern Warfare II. Select Install to download then install the game. As for the installation of the game in physical, you just have to insert the CD in your console and the game will download automatically.
Us44ukd.