You can request an early/late check-in in several ways:
You can specify your intended check-in time while making the reservation.
You can manage your booking online to request a check-in time outside of the standard hours.
You can contact the property directly, using the contact details found in your booking confirmation.
Please note that the property cannot always accommodate this request; they will be happy to let you have your room early if there is availability, but there may be nobody to welcome you if you arrive late at night at a remote apartment. It's always best to check with the property directly in this case, to avoid any disappointment.