First step:
You will first need a web virtual host setup for the hostname you are wanting to get a certificate for. Please open a ticket for this and we will set it up. Then you can follow the rest of the guide yourself.
You can setup letsencrypt on your own like this:
cd
mkdir -p letsencrypt/var/log letsencrypt/var/db letsencrypt/etc
Fill out the HOSTNAME_HERE part and use extra -d HOSTNAME entries for ailases.
certbot --config-dir ~/letsencrypt/etc --work-dir ~/letsencrypt/var/db --logs-dir ~/letsencrypt/var/log certonly --text --agree-tos --renew-by-default --webroot -w ~/public_html -d HOSTNAME_HERE
Then add this in crontab -e:
0 0 */25 * * /usr/local/bin/certbot --config-dir ~/letsencrypt/etc --work-dir ~/letsencrypt/var/db --logs-dir ~/letsencrypt/var/log renew >/dev/null 2>&1
You can list your certificate paths with:
certbot --config-dir ~/letsencrypt/etc --work-dir ~/letsencrypt/var/db --logs-dir ~/letsencrypt/var/log certificates