It should take only two pages to access the prison, although you will need pages one and two. Any other combination won't count for it. Check your archaelogy journal to see what pages you have found. If you do have the first two, make sure you have tried each of Liam's dialogue options, particularly those relating to the mystery.
I would encourage you to find all four, as completing the mystery will award some experience, and help you fully master the dig site.
31-Jan-2021 23:21:55