Continue head down to the first exit on the left to reach Greymoss Mire, then use the grappling hook to reach an NPC.
Once players can pass through the gate to the right of the initial spawn location they'll need to drop down through the scaffolding to reach the door at the bottom-left corner. To join random partners, players will need to first find the Pale Candle in the Ashbourne Village, which isn't an item that needs to be leveled up in Salt and Sacrifice.