Hi Leighton, thanks for posting on the Community
QuickBooks recognises the user-type that you're logged in as, meaning when submitting via MTD as a business owner (when the company is not registered for VAT under an ASA) you'll also need to be logging into QuickBooks as a business user.
You can add yourself as a new user to ABC Consulting (as a Company Admin) with a different email not already associated with QB so that you log in directly to the company file (not via QB Accountant). This will then allow you to turn on VAT and submit the return.
Get back to us below if you have any Q's. :)