There are three possible locations of the NPC that you can hack to get the mission started.
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Next, head to the Ubisoft office so you can find the trailer. You have to reach the ctOS box on the roof to get in their internal security feeds. To do that, head to the back alley and find the Climbax scissor lift. Ride on it and bring it to the arch behind the Ubisoft office, where the ladder is located. Raise the lift until you can hop on the ledge and use the ladder to climb up. Climb over the air conditioning units until you reach the rooftop.
Hack the ctOS back to see the Ubisoft office interior. Open NetHack view so you can identify the desktop PCs you have to hack. Remember that you can keep switching from various security or desktop cameras until you find the desktop containing the trailer. After downloading it, you’ll be able to view the trailer yourself. Once the trailer is over, the mission will be complete.