In the mission "The Outpost" your task is to get to a laptop that is inside of a strictly guarded base.
Near the base, next to the radio antenna, you can find the armored vehicle. Get inside it and wait for your allies to join you. When the team is completed, get inside the base and give attack order to your team mates.
When all enemies are dead, leave the vehicle and get on the second floor of the marked building. There, you can find the laptop and the information inside it will allow you to finish the mission.