Please note that 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 donot 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 donot find SSL option in Plesk Panel then contact our technical team at support@webji.services to verify if SSL Permission reset is required.
