Step 1. Open your folder and go to section 4. Buy the Deflection Vest then click "Go There".
Step 2. Walk to the yellow door. It will turn green, enter it.
Step 3. Walk to the computer solve the puzzle.
Congratulations! "Herbert Security Clearance 4" pin has been added to your inventory.
You've completed Chapter 4 of Operation: Blackout. The next missions will be available on:
Chapter 5 will be released on November 22.
Chapter 6 will be released on November 24.