Please note that the minimum requirement to use free SSL with our web hosting is to have nameservers of our server used in your web hosting ac domain name hosted with us.
If you do not host the nameservers with our server's default nameservers free SSL may not work.
Some related kb articles:
Free v/s paid SSL details at http://kb.webji.services/article/what-is-difference-between-free-and-paid-ssl-certificate
Managing DNS Records | Plesk Obsidian documentation
If you do not find the SSL option in Plesk Panel then contact our technical team at support@webji.services to verify if an SSL Permission reset is required.
