Hello @Rose_Languste and thanks for your answer 
You are right, I have a seperate bell. But does that automatically mean, that the opener won’t work with my current cables? Although the opener can’t recognize when someone rings, but it should be able to just open the door, when I use the app? Or will that also not work?
In the setup steps the nuki app even provides an option, that one does not have a call cable.