Couchbase 5.1.1 Centos install error

Hi All, I was trying to manually install the Couchbase 5.1.1 to AWS linux server. based on “” this link. every step no error but when i try to Configure the instance to use the Amazon EBS directory for storage: I got the unable to connect host http:localhost:8091 error.

for security group, i opened all traffic. pls kindly check the attachement.
There is any config. i need to change?

When i connect to couchbase console, the connection was refused. Pls help mee. Thanks