Loot Crates are items you can open with keys. The only requirement you need to open loot crates is keys. You get keys from playing the game and filling up the timer in the main menu. Loot Crates give exclusive Accessories for Granny and money
You can get multiple keys and Loot Crates by filling the Timed Rewards Bar. You can also get keys using Robux.
Common Key - 50-ROBUX
Rare Key - 150-ROBUX
Epic Key - 250-ROBUX
Legendary Key - 501-ROBUX