Starfield:Delivering Devils

Deep Mines Optional Objective Note
Once you learn Percival's location from Lou, you will have to go to the end of the Spacer dungeon which is the objective of the optional path in the Deep Mines - you will essentially have to clear it whichever option you choose to clear the debt.

Exiting the dungeon unlocks the fast travel point to complete the next stage of the quest. While completing the Deep Mines, a thorough explorer may note a door at the very end which requires a key you do not have - the Drill Waste Room Key. Note that this key is given to you by Lou after turning in the quest stage, and you will then come right back to open that door.