After obtaining these two items, go straight to open the door; there's nothing else around.
After entering through the door, keep moving forward and interact with the lanterns. Interacting with the lanterns triggers cutscenes; there are many lanterns and many scenes to watch (watching them all takes about half an hour). If you don't want to watch, hold E to skip.
There's a section where we need to pilot a boat. After disembarking, remember to pick up the golden item nearby.
The item is the weapon soul-forging material "Langjun's Jade Face".
