This image shows a section of the "Application Roles" page for the DIPC123 application with the DomainAdmin user logged in.

This page lists the roles defined for the DIPC123 application. (Not all available roles are shown in the image.)  From these roles, the "Administrator" role with the  description "Service application administrator role" is underlined suggesting to pay attention to this description - (This role is an administrator at the DIPC application level - specific to this DIPC123 instance).

The action menu for the "Administrator" role is highlighted, which means that it was clicked, and there are four options for this menu: Assign Users, Revoke Users, Assign Groups and Revoke Groups.

The "Assign Users" option is highlighted, suggesting you should click it.