When using Semi-Annual Enterprise Channel, you'll find that Copilot for Microsoft 365 features are not available in your apps. In order to use the features enabled by your assigned Copilot license, you'll need to use the new Outlook for Windows, or move your device to Current Channel.
For assistance with getting your device moved to the Current Channel, contact your internal help desk or technical support. For more information, see How do I find my Microsoft 365 admin?