First things first: the Australian hub is using the official Australian Z wave frequency. That’s different from both UK frequency and the US frequency. So you need to be sure that all of your end devices are operating on exactly the same frequency as your hub. ( and there’s no way to change the frequency after the time of manufacture)
What’s the full model number, including the suffix, of the device that you purchased?
Any zwave device should be found at least as a generic thing. Since it’s not being found it all, it’s probably either not on the same frequency or it needs to be reset.
Also… to set up that hub you need to be using the new app. The new app does not work well with custom DTHs. Have you read all of that stuff yet? But that’s just about getting it to work after it joins, it should join in any case.