How to Install Backdrop CMS on FAMP (FreeBSD 11.2)

Backdrop is an open source and free content management system (CMS). It is a fork of Drupal, mobile-friendly, and fast. You don’t need to know any programming languages to use Backdrop CMS. You can easily create, edit, and manage your content.
Backdrop CMS provides you with a multi-level user experience. This means that you can set different levels of permissions for different people. Backdrop CMS has add-ons, plugins, themes, and layouts. You can use them directly; you don’t need to search for other add-ons or themes. Even if you need to modify its API, you can do this according to your needs.