There are plenty of Australian users of IoTaWatt, so I was hoping someone more familiar with the local equipment would respond, and that may yet happen. From what I can see you do have three-phase supply as well as a three phase solar inverter. There appear to be 8 additional circuits as well.
To monitor everything, it appears you would need:
3x100A CTs for the mains
3x50A CTs for the solar inverter
8x50A CTs for the other circuits.
That’s a total of 14 CTs, which is the capacity of the IoTaWatt using derived reference.
As outlined in the stuff site, it’s best to get the VT and USB power supply locally from one of the sources referenced. When the CTs are installed, they should all be oriented the same way with respect to line/load to avoid problems configuring the derived reference. It would be helpful as well if your electrician would label which mains phase is associated with each branch circuit, and which mains phase feeds the outlet where you plug the VT.