I not positive but I'm not sure the Roland transmits audio via USB. Just run audio cables from the Roland brain to your interface.
My 2 cents only, but I wouldn't bother with audio from the Roland kit. Just connect midi(either midi cables or USB) and put up a stereo instrument track and insert any of the available drum VI plugins(Addictive Drums is the best bargain and can be had on sale for $99). (been doing this with a TD-10 kit for years and it rocks
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