Which Prism Central setting must first be configured in order to add users to a...

 In order to add users to a Project, the Prism Central administrator must first configure an Authentication Directory. This is a service that provides user authentication and authorization for Prism Central, such as Active Directory or OpenLDAP. By configuring an Authentication Directory, the administrator can enable users to log in to Prism Central using their existing credentials and assign them roles and permissions based on their group membership. The administrator can also create local user accounts for users who do not belong to any Authentication Directory.

References:

Nutanix Certified Professional - Multicloud Automation (NCP-MCA) Exam Blueprint Guide, Section 2, Objective 2.5

Nutanix Multicloud Automation Administration (NMCAA) Course, Module 2, Lesson 2.2

Configuring Authentication | Nutanix Community