Collect output of all steps from a single SSM document

Automation, a capability of AWS Systems Manager, integrates with Amazon CloudWatch Logs. You can send the output from aws:executeScript actions to the log group you specify. You can read about enabling the CloudWatch logging on this documentation page.

To monitor the execution status of your automation document, you can use Amazon EventBridge. Amazon EventBridge is a serverless event bus service that allows you to connect your applications with data from a variety of sources. EventBridge was formerly called Amazon CloudWatch Events. EventBridge can add events from dozens of AWS services to your rules, including Systems Manager. EventBridge also supports events from the Systems Manager's Automation capability. See an example of an Automation event pattern here.

You can define an AWS Lambda function as the target of your EventBridge rule. This Lambda function will gather the CloudWatch logs and send them via email. You can use the Amazon SNS service to send emails. A similar solution is described in this blog post.