DJM 450 USB Send and return App development

Hi I would like to develop an effects app for the send and return usb feature for android and ios devices, would anyone be able to help me? I would expect to receive data via an audio device when connected to my macbook but i cant seem to get it to work, of course i can send audio via the usb b port on the back but would like to be able to do this from my android phone. I know that many apps are iOS only, if someone could help me understand why that would be really helpful!