1. Copy the Chain Certificate that appears in the box during the certificate pickup process and paste it into a Notepad file. Be sure to include the BEGIN CERTIFICATE and END CERTIFICATE tags.
2. Important Step: If the certificate pickup wizard includes an extra box for the Chain Root Certificate, it is critical that this certificate be included as part of the chain file.
3. Copy the Chain Root Certificate and paste it into the notepad file right below the Chain certificate. The notepad file will include both the Chain and Chain Root files in a single concatenated PEM file.
4. Save it as ca-bundle.pem. The file should look like this:

Open your server’s httpd.conf or httpd-ssl.conf (some server name it as ssl.conf) file and locate your virtual host entry for the domain to be secured by this certificate. If you are not sure where you configuration file is located run the following command: openssl version -a You will see at end of the command output "OPENSSLDIR:" this is the path that is configured where OpenSSL will look for configuration files Add the following line under the virtual host entry of your site/domain in the configuration file: SSLCertificateChainFile /.pem

The Chain Certificate has been installed.

You will have to stop then start your website for the changes to take effect.