Hey Francois,
In order to get zeroexport working, their are 2 options, from your explanation as I understand it is seems they have supplied half of each option.
Ellie's sells 3 versions on the DTU 1 x single Phase and 2 x 3 Phase.
Likely what they have supplied is a single phase unit which requires the efergy solo to clamp to your mains power line to feed back to the DTU this you can tell by the fact that the DTU has 2 anttena 1 white and 1 black.
If you had the 3 Phase DTU meter which does work with single phase installations this unit has a RS485 port and will connect to the current power meter.
Also the 3 phase DTU's are a couple R100 cheaper.