@Brianne46 The lock I use has a "bridge" so I can program codes and control it remotely, but I had so many problems with the bridge connectivity that I simply disconnected it, and now I send codes manually.
My practice is to make the code the last 4 digits of the guests' cell phone. If you are able to program the lock to issue codes that way, you could simply inform guests that their code is that in the check-in information, and then not actually send a code, if that makes sense.
Are you able to program the way that the lock creates codes?
BTW, on Amazon it says that that lock works with AirBnB. Have you had their tech support involved to see what's not working?