The documentation portal is undergoing maintenance. During this period, you can't create any new user credentials. If you do, you'll need to recreate the user credential after the maintenance period ends.
Effective in version 10.4.0, new advanced properties are available when you configure a Create Cluster task with an Amazon EMR connection in a workflow.
You can configure the following functionality on a Create Cluster task:
Root device EBS volume size. The number of GB of the EBS root device volume.
Custom AMI ID. ID of a custom Amazon Linux Amazon Machine Image (AMI).
Security Configuration. The name of a security configuration for authentication and encryption on the cluster.