@Greg306 Newer host here (and US based) but we installed a Yale lock which has a full integration with AirBnb. There are still some parts of the Yale system that seem to be partnered with August. You could have it where they need to download the Yale Access app or buy an additional keypad (we went with the Yale Assure with Keypad) and ONLY use keypad access. I personally would never download an app for a single Airbnb, so I wasn't going to consider anything that required an app.
We didn't have it set up before our first booking so I just added a temporary key code for the first guest. But each booking after the first has gotten an automatic code generated and sent to them in an Airbnb message. This code starts at check-in time and ends at your check-out time. You can go in there and manually change times if you have offered an early check in or check out. We are on our 4th guest since joining Airbnb last month, and no one has had an issue getting in. If anyone did, I can do a remote unlock from my phone. Hope that helps!