SMTP AUTH uses App passwords which can be created from this link:

https://mysignins.microsoft.com/security-info

For an easy way to enable SMTP AUTH go here

https://portal.office.com/adminportal/home#/featureexplorer

  • Expand Settings and click Org settings
  • Click Modern authentication
  • on the right check the box that says Authenticated SMTP and then click save

References:
https:https://quickbooks.intuit.com/learn-support/en-us/other-questions/emailing-invoice-with-office-365-exchange-stopped-working/00/496092//quickbooks.intuit.com/learn-support/en-us/other-questions/emailing-invoice-with-office-365-exchange-stopped-working/00/496092