Some systems can only be opened via the intercom if the doorbell was rung before. The intercom needs an activation (the ringing).
The Nuki App guides you through the configuration, considering this particular feature of your intercom. After configuring the Nuki Opener, only "Ring to Open" can be activated.
Since you have to ring before opening your door, you cannot open your front door via the Nuki App.
Note:
Please remember that you need the help of a second person to set up the Opener.