CT ECS10-50 with voltage output

Hello, I recently bought the following CT - ECS10-50 to use it with IottaWatt. Only after installation, I realised that it has voltage output instead of current output. However, for approximate measurements, I am intending to keep it until I get proper CT with current output.
So my idea to use it wit IotaWatt is to set the value of the burden resistor in the IotaWatt setting to the parallel value of both burden resistors (internal IotaWatt burden is 20 Ohms).
However I don’t know the value of the burden resistor inside ECS10-50 with 333mV output.
Experimental measurements with 2kW load and adjusting the value on the IottaWatt gives me about 4 Ohms burden in the ECS10-50 (so the total is 3.333 Ohms as a parallel combination of 4 Ohms and 20 Ohms).
In the IottaWatt setting, I left the other CT setting to ECS1050 (didn’t change it to custom).

Any user can help me with setting the propper values of this setup without hardware modification (removing the burden)?
Precision is not a big deal.
Thank you very much.