@Lynn120, So you send the check-in information, i.e., key pad code prior to the guest arriving but your guests do not have the information with them, right? For me when I travel, I had one host used a key lock box and one host used a key pad. What I liked about the key pad was the host coded it with the last 4 digits of my phone number. I could remember that better than some other code that I might have to remember to bring with me.
I don't know if you have traveled on Air BNB, but being a guest a few times has made me a more considerate host. It might be helpful for you to pose this same question to the guests and ask their input as to what would have made the check in smoother. You can send them a private message if they have already checked out.