Many users would like to utilize the LetsEncrypt provider for AutoSSL on Ubuntu systems. The installation process is different for Ubuntu than it is for CentOS and its derivatives.
Currently, the standard way of installing Let's Encrypt for AutoSSL does not work on Ubuntu, instead, you need to use APT to install the package.
Simply install the cpanel-letsencrypt-v2 package:
apt install cpanel-letsencrypt-v2