So, I made it to Longstall. And now I have NO IDEA what to do.
I talked to everyone, I tried going into all the buildings... Nothing to do.
You'll need to talk to the bartender south of the city and she will tell you about the security guard guarding the entrance to the dungeon. You'll need to be there by midnight and you just have to wait for a couple minutes before you see a ZZZ bubble show up above him then you can walk past him.
But there is a bug I came across that softlocked me and I can't enter the dungeon or see the MC.