This domain appears to use CloudFlare. When you use CloudFlare, they provide SSL for the connection between CloudFlare and your visitors, but you typically also need to secure the connection between CloudFlare and your origin server in Google Compute Engine.
Unfortunately, the default method certbot uses to verify your domain (tls-sni-01) will not work with CloudFlare intercepting your SSL, because it relies on being able to temporarily present a special certificate. Since your server is hidden behind CloudFlare, Let’s Encrypt will only ever see CloudFlare’s certificates and this does not work.
You can instead force certbot to use a different method of verification called http-01 or webroot authentication, which just places a special file in your web directory and typically works fine with CloudFlare. In order to use it, you will need to figure out the local directory on your domain that contains the files that are served to the Internet. In most distributions, this is located at /var/www/html.
In that configuration, you would invoke certbot like so:
sudo certbot run -a webroot -i apache -w /var/www/html -d magentamagazine.co.za -d www.magentamagazine.co.za
