The boat manual also includes a diagram of the bilge pump system with sump location. That is where your switch lays. The manual switch simply overrides the high water switch and turns on the common pump. It is quiet, so you likely won't hear it running. Regardless, start lifting sole boards until you find the bilge sump and switch - these are critical items that should be diagrammed and posted for all crew members awareness. Should be near the keel bolts. When you find the sump, fill it with water and observe that the switch activates the pump and it evacuates the water. Then do it again using the manual over-ride switch.
Find the pump also, check the intake filter and keep it clear of debris. Your system is the typical modern Beneteau setup.