You need to ensure that users can use an external system as a knowledge source...

The correct answer is Connectors . Microsoft documents that Microsoft 365 Copilot connectors are used to bring external, line-of-business data into Microsoft 365 Copilot so users can search, reason over, and act on content from non-Microsoft systems. Microsoft also states that admins must enable and configure Copilot connectors in the Microsoft 365 admin center , and once configured, those connectors can be selected as knowledge sources for custom agents. This directly matches the requirement to let users use an external system as a knowledge source for custom Microsoft 365 Copilot agents.

This is why the hotspot in the Copilot area should be set to Connectors , not Overview, Agents, Search, Billing & usage, or Settings. Overview provides status information, Agents is for agent management, Search is for Microsoft Search experiences, and Billing & usage is for metering and consumption tracking. The specific admin feature that enables external enterprise data sources for agent grounding is Connectors . Microsoft further explains that configured connectors can expose external knowledge securely and respect source-level permissions when used in agent scenarios.