Abstergo Scene 4

You'll receive LV3 security clearance at this point which will allow you to explore more areas even more. That means you should have access to all the Sticky Notes and hackable computers/ terminals. I'll leave the exploring to you since there are no missable Sticky Notes and Computers. You can always go and find the ones you missed even after you finish the game.

Make your way to the marked security room. You should find another sticky note along the way. (Sticky Note 18) Now enter the room and hack the security computer. The code is 3757.

After watching the security feed, access the cloud server and hack it as well. The code is 3777. After completing the hacking sequence, you'll have to manually hack the remote computer. A new database entry will be added (Abstergo Entertainment: Aget of Cutthroats) and a cutscene will trigger.

After the scene, head back to your room and log in back to your animus.