I don't think there are any official information. Since the original battery has 4000mAh and a maximum discharge rate of 8C (in reality even lower) the power supply is a maximum of 96A. Divided by 6 equals 16A per motor. I don't think the ESCs are rated for a continuous current of more than 20A. The peak current might be a little higher.
This fits to what I would expect a multirotor of that size to use. A high quality ESC with 20A and good cooling should be enough for its needs. Maybe 30A if you want to be safe.