An AWS CloudWatch API Key is required when connecting SQLBench to an AWS RDS for SQL Server instance.
The AWS CloudWatch API Key allows SQLBench to list AWS RDS database instances in the subscription, and collect "host" telemetry such as CPU utilization, Disk space, Available Memory etc.
This article provides step-by-step instructions for how to create a key with the necessary permissions to be used when connecting SQLBench to an AWS RDS for SQL Server instance.