Do you want to add a Divi Library element, such as a section, row or module into a non-Divi Builder page or into another Divi Builder module? If so, there are several plugins out there which will help you generate a shortcode which you can use to display the Divi Builder / Divi Library elements wherever you need to:

https://wordpress.org/plugins/simple-divi-shortcode/
https://divicake.com/products/divi-shortcodes/
https://www.elegantthemes.com/blog/divi-resources/divi-plugin-highlight-ac-shortcodes

They are all more or less equivalent. The first one is free, so you may want to start with that and move to the others if it doesn't do what you need.