The in5 WP embed plugin is designed to work with WordPress's Block and Classic editors.
Elementor, Divi Builder and other 3rd-party editor plugins, interfere with the in5 embed plugin, so in5 is not likely to work directly when editing with those custom editors.
However, there is a way to insert in5 content into these editors...
1) Create a draft post or page using one of WordPress' default editors (I recommend doing this in a separate browser tab so that you can keep it open).
2) Insert in5 content using the in5 embed plugin.
3) Access the underlying code (via the Hamburger menu > Edit as HTML in the Block editor, or via the Text view in the Classic editor).
4) Copy the <iframe> code.
5) Switch back to your 3rd-party editor.
6) Add an "HTML" block, e.g., Code in the Divi Builder (left below) and HTML </> in Elementor (right below), and paste in the code.
You'll likely immediately see your content as soon as you've inserted the code (image above shows content inserted into Elementor).