To make use of a wildcard SSL, you must first create a wildcard subdomain in cPanel's Subdomains interface (cPanel → Domains → Subdomains).
This will automatically create the necessary A record in the local DNS server. Note that this plugin won't issue SSLs for wildcard subdomains whose DNS is not hosted locally!
To install the plugin, first log in to the server via SSH as the root user (remember that KnownHost sets the SSH port to the non-default value of 2200 to help prevent SSHd login abuse on our VPS, cloud, and dedicated servers).
Now, run the following command:
A successful installation should look like this:
You should then be able to accept the Let's Encrypt Terms of Service in WHM's Manage AutoSSL interface. Log in to WHM and navigate as follows:
WHM » Home » SSL/TLS » Manage AutoSSL
Select the Let’s Encrypt option under the Providers tab. The interface will then display the Terms of Service section.
Review Let’s Encrypt’s Terms of Service. Select the I agree to these terms of service option and click Save if you agree.
Lastly (and optionally), select the Recreate my current registration with “Let’s Encrypt option to update your provider registration.
Now, click the Manage Users tab to run AutoSSL for single users or click Run AutoSSL For All Users in the blue box as shown in the previous image.
You can now click the Logs tab, click Refresh, and see the log entry appear at the top of the list of logs for the user(s) you just initiated AutoSSL checks for. Click on the log entry and click View Log to review the log entries.
If there is a plus sign next to the log entry in the shown in the list of logs, AutoSSL hasn't completed for the user(s) yet. The amount of time required for AutoSSL to complete can vary depending on the number of users, however, it typically takes 10-15 minutes for a single domain from the time that the SSL is initially requested to when the SSL is issued and installed (provided no errors occur).
You'll see green text at the bottom of the log entry denoting that the SSL was installed successfully for the wildcard subdomain. You can then test to confirm the wildcard subdomain has a valid SSL using any number of SSL testing sites available online.
If you have any trouble following this tutorial, feel free to open a ticket with your KnownHost Support team and we'll be happy to help! :)