Zoom computer audio not sharing keyboard midi for piano lessons

[WonderousSound2]

Hi there,

SOLVED!

SOLVED!
In my losing my way in the midst of what became a puzzle, I had forgotten to leave my DAW open.

I am delivering keyboard/piano lessons online and am have difficulty with sharing the computer audio to hear the midi of the keyboard.

I have tried several potential solutions, though as yet still cannot hear the sound.

The midi works when going through Garageband.

I've set up the midi for the Zoom input/output in midi settings on Garageband. When in Zoom I click 'share computer audio' and no sound comes out. The small box to tick for option of 'share sound' is greyed out.

I have also tried going through my audio interface with the leads from keyboard to interface. Then choosing that as the speaker option.

I've tested out the different options of sound including for 'live musicians' and get the message there's a problem turning it on.

The sound is set to only me to share, not multiple participants. 

I have updated Zoom, and restarted. 
I'm using a Macbook with High Sierra.

I trust someone can help, I'm in quite a puzzle with it.

Thankyou!