To enable Self-Service (formerly Calm) policies for scheduling and approval tasks, the minimum requirement is the Policy Engine VM. The Policy Engine VM is responsible for managing and enforcing policies, including scheduling and approval processes within Nutanix Calm.
Reference:
Nutanix documentation on Policy Engine.
Nutanix Best Practices for Scheduling and Approval.

An event trigger is a type of trigger that can be used to execute a playbook when a specific event occurs in the Nutanix platform. An event trigger can be configured with various parameters, such as the event type, the target VM, the target VM category, the target project, and the target user. In this scenario, the administrator wants to be notified when a subset of VMs within the Environment:Dev category is restored from snapshot. Therefore, the event trigger should have the following parameters:
Event type: Snapshot Restoration. This is the event that indicates a VM has been restored from a snapshot.
Target VM: VMS in Environment: Dev. This is the filter that specifies which VMs are relevant for the trigger. By selecting VMS in Environment: Dev, the trigger will only apply to the VMs that belong to the Environment:Dev category.
Other parameters: These can be left as default or customized as needed.
Reference:
Nutanix Multicloud Automation Administration (NMCAA) Course, Module 3: X-Play, Lesson 3.2: Creating and Managing Playbooks, Slide 13: Event Trigger Nutanix Certified Professional - Multicloud Automation (NCP-MCA) Exam Blueprint Guide, Section 3: Validate Blueprints, Playbooks, and Automation Settings, Objective 3.1: Determine the causes of a Playbook execution failure

To deploy blueprints to Calm SaaS and execute them, the administrator must first configure a site-to-site VPN tunnel and a tunnel entity in the environment where the blueprint will be deployed. A site-to-site VPN tunnel is a secure connection between two networks over the internet that allows Calm SaaS to communicate with the on-premises or cloud environment. A tunnel entity is a logical representation of the VPN tunnel in Calm SaaS that contains the tunnel configuration and credentials. The administrator must also register the environment and the provider accounts in Calm SaaS before deploying the blueprints. Reference: Nutanix Certified Professional - Multicloud Automation (NCP-MCA) Exam Blueprint Guide, page 9; Nutanix Calm SaaS User Guide, section 3.1.1 and 3.1.2.

In the Guest Customization section of a blueprint for an AHV Linux service, you can apply a Cloud-init script. Cloud-init is a widely used method for customizing cloud instances during boot time, allowing for automated configuration of the virtual machine's operating system.
Reference:
Nutanix Calm documentation on Guest Customization.
Nutanix Best Practices for Using Cloud-init.

The alert indicates that Calm Showback is unable to reach the Beam service. One possible cause mentioned is that there is no DNS configured in Prism Central. To resolve this issue, the administrator should ensure that DNS is properly configured in Prism Central to allow for name resolution and internet connectivity required to communicate with Beam services.
Reference:
Nutanix documentation on Configuring DNS in Prism Central.
Nutanix Best Practices for Calm and Beam Integration.