There are 3 options to configure Step Functions state machine as a target in EventBridge
https://docs.aws.amazon.com/eventbridge/latest/userguide/eb-targets.html
https://docs.aws.amazon.com/step-functions/latest/dg/tutorial-cloudwatch-events-target.html
https://docs.aws.amazon.com/step-functions/latest/dg/cw-events.html
- step function target account: event bridge -> step function
- event source account: source event bridge -> target event bus
https://docs.aws.amazon.com/eventbridge/latest/userguide/eb-cross-account.html