Suppliers are not getting credentials after Auto approved to Prospective / Spend Authorized

Summary:

I created a supplier using office email Id as well as Gmail email id. Using the supplier creation URL in 'Configure Procurement Business Function'

Able to register the supplier details and finally it approved and status changed to Spend Authorzied. Similarly for Prospective.

But, supplier user not received any email notifications with login credentials for the same. As in the attached screen it says "User Account Information will be sent in a separate email" but there is no email.