As stated in your booking confirmation (which you have received via email after making the booking), you will get the electronic code for the door only one day before check-in via email (mostly in the afternoon or evening). It’s not possible for us to send that code sooner as we have to program it every time new with each booking and you also anyway don’t need it sooner ;). So please no hurries.
The code will be only valid during your stay from check-in at 15:00 until latest check-out 11:00.