@jroman In the first step a Nuki Bridge is a device to get remote access to your Smart Lock. If you have a Keypad you can create entry codes for that and just give those to guests.
Additionally you can use the Bridge API (locally) and the Web API (needing a Nuki Web account) to automate tasks. Still authorizations are created on the device itself (locally ore remotely if online and reachable through the Bridge).