Zammad is simply a web based open source helpdesk system.
I got the plugin resolved by rereading the Zammad's setup Elasticsearch. Look like my 2 mistakes were
- Since its version 7 and not 8, I was using HTTPS instead of HTTP.
- There were added texts that should not be in the yml file, because they are commands. Its the long error code I had initially posted
$ zammad..., etc. (I should had realized earlier with the $.)
Thank for trying to help out dadoonet. The problem is solved.