With the data secured, your new objective is to escape the RPD and head to the extraction point. The path back through the RPD will be even more dangerous than your entry. Expect new enemy spawns, including Tyrants (Mr. X). Tyrants are incredibly resilient and powerful; they cannot be killed easily at this stage. Your best strategy is to avoid them, stun them with explosives, or focus fire to temporarily incapacitate them while you run past.
Navigate through the now heavily infested corridors. The mini-map will guide you to the exit. Be mindful of your ammo and health. Use any remaining health items strategically. Once you reach the exterior, you'll need to fight your way through a final gauntlet of infected and possibly some UBCS forces who have arrived to contain the situation. Reach the designated extraction zone to complete the mission.