
The figure above provides an overview of the user authentication process. For a business user to have access to a specific application on the Cloud services, their identity needs to be present within the designated identity provider service of the SAP S/4HANA Cloud, public edition. The identity provider service is used to authenticate a user's login and access to the SAP S/4HANA Cloud, public edition services requested by the business user.
As an administrator, you can import new business users or update existing ones for a specific cloud application with a CSV file into the authentication service of your SAP Cloud Identity Services. You can also send activation emails to the users that have not received activation emails for that application so far.
Result

An activation email is automatically sent out to the users that are not yet active for the selected application.
Best Practice

SAP recommends notifying users to verify their junk email and spam filter settings to ensure that they can receive the activation email with the subject Activate Your Account for [System]. To activate their account, they have to click the link displayed in the activation email. They'll then be able to set a password for their account.
Summary
You now know why IAM admins need to import users to the Identity Authentication service and how to do it. Well done!