This short article will guide you on:"What are Vaults in Apex Legends?" and "How to get Vault Keys in Apex Legends?" If you want to find the answer, just follow this article.
 
What are Vaults in Apex Legends?
The World's Edge map in Apex Legends features three Vaults, and the locations are marked with small lock icons seen on the map below. These special rooms are full of Rare (blue) and Epic (purple) items that can help your squad make its way to the final circle. 'Apex Legends' Season 3 features three Vaults on World's Edge. These are the locations.

 

 
How to get Vault Keys in Apex Legends?
Like many of the other items that you can find in Apex Legends, Vault Keys are an special addition that can be found scattered around the game world. If you want to get your hands on a Vault Key, then you’re going to need to look out for the weird polygonal orbs that have now begun to appear around World’s Edge. These orbs often shine different colors and when destroyed will drop a ton of loot. Unfortunately, nabbing a Vault Key isn’t guaranteed, so you’ll want to go around look for these items until you manage to get your hands on one. We haven’t found any dedicated spawns for Vault Keys just yet, so just drop into the match and look around for colored orbs floating a few feet above the ground.
 
There are three vaults on the map: one near Lava City, one near the Train Yard, and one near the Geyser. All three will appear on your minimap once you get a key. Keys have a chance to drop from loot drones when you shoot them down. It seems the keys drop from drones that have a red tile; the color of the drone when you shoot it doesn’t appear to matter.
 
In all cases, the loot vaults are locked behind golden double doors with glowing orange locks. They're all buried underground in the small tunnel sections of World’s Edge, too, populated only with small amounts of supply bins and weapon spawns. These tunnels and rooms are excellent places to camp: whether you’re passing through or looking to use your shiny new loot vault key, it’s wise to proceed carefully. Your best bet to get in safely is to bring Crypto, who can scout the area with his drone pal before heading in. Equally, take Bloodhound: they can check for recent signs of movement and scan to check for potential ambushes. Wraith can also be useful to portal in and out. No matter whom choose, avoid lingering near the vaults, they’re certain to become hot spots once keys start appearing.
 
Once you find the vault key, you can now open the vault. You'll be rewarded with several purple-tier and gold-tier items, including purple and gold backpacks, knockdown shields, body shields, helmets, and a few weapon attachments or phoenix kits. By the way, hope this guide can help you!