A lot of ETL work is done in other systems. Many of those other systems' schedulers/orchestration is inferior to that of Airflow. This plugin allows Airflow to use AWS SQS to communicate between Airflow and these other systems.
The primary requirement is a sensor. The sensor would await in a running state for an SQS message. Once an SQS message for that dag, task, and execution_date was received, it would change to a success state.
The sensor would have a timeout parameter after which it would fail. Whether it went into failed or up_for_retry would depend on how num_retries was set for the sensor.