All 4 of olivias crystals are found in the ground sometimes when you press 'E' to dig em up you will also sometimes pick up the crystals at the same time, this will be fixed later on and one is at one of the corners by the pool in a plat pot that can be a little hard to grab spam crouch and 'E' and you should be able to grab it (this will also be changed & a counter will be added to track how many)