Record with the track that matches what you are playing. Headphones while you record, so the track doesn't bleed into your microphone.
Play the etude along with this recording. Drum set is the exception — play your etude unaccompanied.
Everyone recording the optional improv portion plays over this.
Record your bassline over the top of this one.
Comp along with this for your second recording.
You may not get every note of this material under your fingers before the deadline. Don't let that stop you from auditioning. Do your best and record it.
Questions about your scale, the etude, or how to record and upload — ask any time before the deadline.