From this page of the Disco Elysium guide, you will learn where to find Measurehead, one of the main NPCs.
Measurehead is one of the characters that you may encounter while playing Disco Elysium. This man belongs to the Dockworker's Union and guards the door leading to the office. Measurehead can be useful, for example, when doing the Getting the body down quest.
Walk towards the Frittte kiosk and you will notice ongoing protests. On the left, in the location marked in the image above, you will find the entrance to the upper level of the port.
Once you get to the upper level, turn right, and walk forward. Eventually, you will reach Measurehead and be able talk to him.