Convert the tutorial from Andrew Kramer using After Effects into Blueprints. It should follow the same logic.
Convert the audio file into 2 parts (treble and bass), keyframe those parts, and use those keyframes on the object you want to animate. It shouldn’t even have that much cost to it, since it would be rendered into a “static animation”. If you were to do a “real-time” animation, where the user could chose whatever track that they wanted from their own selection, that would be pretty costly, since the engine would need to do the keyframing / conversions in real-time.