Redshift-Cluster User Auto-Create

We are using SAML identity provider for user authentication. We have created an IAM role through which we could access the Query Editor, but the user is not created afterwards. How to auto create user while logging into Redshift cluster?

We have added the following policy to the role as well "Effect": "Allow", "Action": "redshift:CreateClusterUser", "Resource": "arn:aws:redshift:us-east-1:AccountNumber:cluster:cluster-name/${redshift:DbUser}"