It's nice to see you here in the Community, @TestAD.
I'd like to ensure you'll get pointed in the right direction so your API concern gets addressed.
To help verify the reason you're unable to receive an email for the two-phase-authorization, I recommend contacting our Intuit Developer. This is the forum that provides the right amount of information for your concern as they enable your application to access the program.
You can visit them though this link: The Intuit Developer.
Lastly, I'd like to share these links below that contain details on how QuickBooks Online and QuickBooks Desktop works for your reference:
If you ever have questions or need anything, I'm just a few clicks away. Have a good one!
