Availability
Quest gameplay recordings show the Mill as a playable location. Steam and PS VR2 evidence reviewed for this site does not show it, so this guide remains Quest-only.
Before looking for an unlock
Update the game, confirm your current objective chain, and check whether earlier areas are complete. Avoid buying or using a progression shortcut based on an old video without checking what it does in your current build.
Verification queue
The exact current Quest version, keycard path, task order, and entitlement rules still need a clean-build capture. We will not copy those steps from an undated clip.