The following link uses CloudFormation to create a stack using the AWS console:

Launch RedisCloud template

You can then use the Outputs tab to find the data needed to complete the creation of a Cloud Account.

If you prefer to use the AWS CLI then the command you need is shown below, substituting your profile where it says YOUR_PROFILE_HERE (or using one of the other methods as per the AWS CLI docs)

aws cloudformation create-stack --stack-name RedisCloud --template-url \
https://s3.amazonaws.com/iam-resource-automation-do-not-delete/RedisCloud.yaml \
--capabilities CAPABILITY_AUTO_EXPAND CAPABILITY_NAMED_IAM CAPABILITY_IAM \
--profile YOUR_PROFILE_HERE