You do not need a lockbox specifically, but you do need a secure access method for self-check-in. The options are a traditional key safe, a smart lockbox, or a smart lock. All allow guests to access the property without you being present. Airbnb requires you to select a check-in method in your listing settings and provide clear instructions. A lockbox or smart lock is the standard approach. Leaving a key under a mat or in an unsecured location is not acceptable and may invalidate your insurance.