Plesk SSL
If you are currently using plesk then you can install an SSL certificate by going to your plesk panel and selecting the tool "SSL/TLS" once here you should see a green button that says "get it free" along with some text about Let's encrypt, press that green button and the SSL shall install automatically for you.
cPanel SSL
You can install an SSL certificate on the domains using a tool in cpanel called 'Lets Encrypt' simply visit that tool and there should be two tables, one for the currently installed domains and the other for domains that you can install SSL on. Click the "issue" button on the domains that need SSL and it will take you to the issue page where you should be able to confirm this.
Please contact support if you have issues with either of these.
