Near the beginning of Dead Island 2, you’ll take part in the Desperately Seeking Emma quest. You’ll slay some zombies, and then burn some with a giant wheel. At this point, you’ll start the Help the Injured Couple portion of the quest. However, when you try to talk to the NPC, Joshua, you’ll see a Campaign is Installing message, halting you from progressing the story.
The good news is the game isn’t broken. The bad news is there’s nothing you can do except wait for a bit. The Campaign is Installing error happens when you start playing the game before it’s fully downloaded.
Admittedly, you don’t get to play a whole lot of the game before you reach this point, so you may be stuck here for an hour or so. Just keep an eye out on the download progress, and once it’s completely finished, the Campaign is Installing error will disappear and you can continue on with the story.