Hi @Billie8
I've had many lockboxes and keyless door locks. It depends on what you're looking for:
1. Lockboxes are more simple. You will store the keys inside the lockbox and you'll give the access code to your guests. Masterlock is the most known brand. I have 2 units from them and it's worked very good so far
2. Keypads: You can configure several access codes (as opposed to lockboxes) and it will open the door directly (no need to keys). You'll have to install it to your door. There are quite a few brands: Schlage, Kwikset, yale and more
3. Smart locks: These are like keypads, but you can manage / monitorize them from anywhere with an app. Please notice you'll need a smart hub (like a router) to have it working online. These are more expensive but you can manage them anywhere. Perfect if you are not always around the house you're renting.
I remember Airbnb promoted igloohome. Those smart lock have the feature to synchronize with Airbnb (for generating new access codes on check ins)
Best!