Premise CodeDeploy Agent, session arn

I'm setting up an on-premise CodeDeploy Agent.

The instructions here have an issue.

I completed Step 2: Generate temporary credentials for an individual instance using AWS STS

I'm trying Step3: Add a configuration file to the on-premises instance

The instructions say to use the iam-session-arn noted in Step 2. However, there is no session arn to note in Step 2. There's a session name, there's a role arn. No session arn.

What is the session arn that is being referred to?