My understanding is it simulates mining. So therefore no resources used on your phone. They just look at the specs of your phone and you get tokens based on that. It is essentially still mining, just a simulation of it. As long as you get tokens for using it that is what mattters. Better to mine like this than melt your phone.
The actual mining will be on PCs.
Is this actually correct? Just asking. But if it is correct, then it would be much more convinced of the system really being sustainable.