Could you tell me which Zend Server version we talk about here and which CloudFormation template? There are 2 sources for CloudFormation template:
1. There is a CloudFormation template generator on our website - http://www.zend.com/en/products/server/cloudformation
2. AWS Marketplace has CloudFormation template for each of our products
It would also be easier if you could post CloudFormation template here or send it by email to firstname.lastname@example.org
P.S. If you use latest version of Zend Server 8.5 or 9.0, ZEND_CLUSTER_NAME is probably unused and can be safely ignored, it will be removed when next minor version of Zend Server is released.