Coupling your Homey is done via the Bridge HTTP-API. You will need the following parameters for setup:
In the Nuki app, you can search for your Bridge from the menu item “Manage Bridge”. By clicking on the Bridge icon, activating the API quick connection and the HTTP API, you will get the required parameters for integration.
This app allows to control the Nuki Smart Lock using the Homey by Athom B.V.:
Hi stephan
It all sounds good to me if you’re using your phone with the homey app, how would you do to make Niki send a signal to homey (say unlocking in example) using the keypad or fob or iwatch and not the homey app ?
Tx in advance 
Apperently above proces doesn’t work anymore. Where should I enter the credentials and so on? I just get a blank screen when I try to add Nuki in Homey. Could anybody help me out?
perhaps this can help: Protocol from Nuki per Webhook to Homey? - Questions & Help - Homey Community Forum