I contacted the Siteground Hosting Support on this and they tried Installing LE too from their End and couldn't so they sent me this messge:
We have carefully investigated the issue and it turned out that Let's Encrypt service is blocking the requests, because the domain name(360.com.ng) or the domain's TLD(com.ng) is in their block-list.
In that case, you should contact the remote service's support team and to request more information about the requirements for removing the domain from the blocked domains list. You could post the question directly in the official discussion board(https://community.letsencrypt.org/) or by contacting them via email(https://letsencrypt.org/contact/). Once the issue is resolved on their end, you could install the certificate from cPanel -> Let's Encrypt tool.
Should you need any other assistance, please contact us again.
Dimitar Petrov Dimitrov
Technical Support Team
PLEASE HELP, WHAT DO I DO, THANKS!