You can find additional details on getting started with Agent 365 here Agent Overview Page in Microsoft 365 Admin Center - Microsoft 365 admin | Microsoft Learn

Agent 365 provides IT and security with a control for agents used by users across their organization. 

Agent 365 licenses are required only for users of agents that employ premium features of Agent 365. This covers all agents that work on behalf of the user (and leverage the user's identity). 

The admin doesn't need a license unless they are also using agents as described above. Users who create agents also don't need an Agent 365 license, unless they are using agents as described above.

To make it easier to manage and plan, we recommend licensing groups of users who are actively using agents.