Event Manager displays all events generated by event handlers.
When ADOMs are enabled, each ADOM has its own event handlers and lists of events. Ensure you are in the correct ADOM before viewing Event Manager. See Switching between ADOMs.
You can use predefined event handlers to generate events for Event Manager. There are predefined event handlers for FortiGate and FortiCarrier devices. For other devices, you can create custom event handlers.
Event Manager displays events from Analytics logs, not Archive logs.