You can also buy a 240v to 48v dimmable power supply, that you would attach to any 240v smart dimmer. It converts the dimming of the 240v to the dim equivalent starting at 48v.
I use one similar for some 12v LED lights in my theater, using a 120v Zwave in-wall dimmer to dim the 12v lights through the power supply. It works great!
They are available on US Amazon, not sure about UK.
Note: 240 watts at 240 volts is 1 amp, so it just needs to handle up to 1A
It is interesting why many smart switches and dimmers are rated for 600w for incandescent, but only 150w for LEDs. I found this is because of the inrush current, where LEDs can take over ten times more current than what they use in steady state, not only when they are first turned on, but also during each half-cycle if powered by AC. Since you are dimming DC, you only have to deal with the inrush when the lights are first turned on, but that can climb to 240w, apparently, for your lights.
So I see now why you need something that can handle 5 amps at 48v, or 240w, if powering the lights directly from the dimmer, to account for inrush. Your LEDs probably take more like 24w in steady state.
Back to your original question, I think that the Zigbee dimmer you originally posted will most likely work with the Generic Zigbee Dimmer driver built-in to Hubitat, so I would just buy that. Every generic Zigbee device (plugs, relays, etc) I've bought is able to use the generic Zigbee drivers in Hubitat, if they are just basic devices, like that dimmer.