SDR Sharp isn't compatible with any SDRplay RSP unless you have an old version of it (sorry, I couldn't tell you which version that would be). I think there's info on forums and possibly downloads available there, but not directly from Airspy. They had a snit and decided not to allow compatibility. But if using Windows, HDSDR and SDR Console are two of the best options. SDRuno is improving and will be made available on macOS and Linux when they get around to version 2.0 (no timetable for that, my guess is at least a year away and probably closer to two).