You can start the quest by going to the entrance of the ruins and talk to the npc there.
Investigate the Ruins
Go further in to the ruins and interact with 3 lion statues. All 3 are somewhat close to the center area and they are always close to an orange crystal.
Ask the locals of Qingce village
Go to Qingce village and talk to Granny Ruoxin. She is very close to the teleporter.
Search for fragments near geo statues
Go to the designated area on the map, or you can teleport close to it and climb up. Once there you will need to interact with the lion statues in a specific order: Middle, bottom right, up left, up right, and bottom left.
You will then have to climb up to the highest mountain in Wuwang Hill, where you will see some more lion statues, and you will also need to interact in a specific order as well. Start with the one close to the tree, as shown in the picture above, then the second lion to the right of that, then go right 3 times, then left twice. Pick up the treasure and go back to granny.
Find a way into the vault
Go to the designated area and find the waterfall. The entrance is just to the right of the waterfall. Once you're inside you'll have to fight a lot of strong enemies, so you need to be prepared for it. To complete the quest, go back to granny and you will get an achievement for "Crouching Dragon, Hidden Chi".