They were testing (at a different scale, with a different powerplant) their air intakes for the engine which are designed to enable conventional turbofan engines to operate at supersonic speed, plus some control systems. And no doubt demonstrating to investors that they could fly something at supersonic speed before they ask for the funds to design and build a new powerplant and airliner-scale airframe...

It was originally envisaged as a maiden flight that would happen within a couple of years of founding, but aerospace is hard.