Docs feedback: EKS cluster creation script fails with error "ClusterSecurityGroupId not found".

I am running the EKS bootstrap script based upon this doc:

https://docs.gitlab.com/charts/installation/cloud/eks.html

using K8s 1.13

and it fails with the error message:

Attribute: ClusterSecurityGroupId was not found for resource: gitlab-cluster. Rollback requested by user.

I suspect a prerequisite step is missing in the docs or there is an error in the script. The template created by the script validates cleanly in CloudFormation.