Hotel booking is on your own initiative. DGI-byen offers hotel accommodation, but a wide range of hotel rooms of different standards and prices are available close to the conference center.
It is strongly recommended that you reserve your hotel room as early as possible. Copenhagen is the host of several conferences during the summer and hotel room reservation may be difficult.
For guidance, please refer to this link http://www.visitcopenhagen.com/copenhagen/hotel-guide or one of the many web services for booking hotel rooms.