I'm not 100% on eu but for most wired in ZigBee devices you want 3 wires for it to be always on. 2 wire I think some people have made work anyways using a capacitor or something but that's too sketchy for my liking. Sometimes the corresponding light recepticle has 3 wires instead, at least in one of my previous homes in Canada, and I was able to put the ZigBee switch in there instead. My current house is about half and half 2 and 3 wire and I'm just shit out of luck on those because the ceiling boxes are all 2.

Sorry 2 or 3 plus ground which is bare here. Edit: also I think the capacitor was to prevent the 2 wire versions of the switch, which are different, from flickering