nixCraft published a tutorial about securing Apache with mod_md Let’s Encrypt on Ubuntu 20.04 LTS.
How To Secure Apache with mod_md Let’s Encrypt on Ubuntu 20.04 LTS
Explains how to install and configure Apache with a mod_md module to secure traffic with Let's Encrypt free TLS/SSL certificate on Ubuntu 20.04 LTS Linux.
How To Secure Apache with mod_md Let’s Encrypt on Ubuntu 20.04 LTS