To get this you have to activate the switch in the lab on the bottom right side of the map. It’s in the blueberry hedge (bush). Make sure you have decent armor and weapons before going here as well or you will die to “Orb Weavers(Spider) and baby spiders. You also wanna bring a “lean to” to set your spawn point just incase you die. Here’s a video guide on how to find the switch for the lab:
Credit to “Magic Flyin Potato” on YouTube for guide.