My question is kinda similar to this one: Certificate for just a subdomain
Let’s say that
example.com is running on server A without HTTPS. The guys running the site has hired me to build
sub.example.com which I host on server B. They don’t give me access to server A. They just point the records in server A for
sub.example.com to server B’s IP address.
Can I still use Let’s Encrypt?