The pump is mounted in a standard 35 mm hole next to the tap, with a refill reservoir under the worktop that you top up from above.
Mounting
Push the pump through the extra 35 mm hole, fit the rubber ring and tighten from below.
Reservoir
Clip the refill reservoir to the underside of the pump.
Refilling
Refill from above by lifting the head — no need to open the cabinet.