Drop zones are Bycyklen stations without (active) docking points.
Press 'End trip' in the app to end your trip in a drop zone. Please note, that the payment continues until you have logged out in the app and locked the bike securely using the lock on the rear wheel.
If you want to use a bike from a drop zone, just log into the app as usual.
The drop zones are usually marked with striped tape or boards, but if they have been removed, check the Bycyklen station’s status in the app or in this overview.