HTML Embed, List of all collection

I’m want to call a field from all collection and display them using javascript. I see that this is close, but was closed: Access collections via html embed?

Also, I see that this can be done more or less with the CMS api, but I’m not sure how to use that within the custom code embed.

How do I go about calling collection data within the HTML embed?

Here is my public share link: LINK
(how to access public share link)

You can’t use API without third-party hosting and a custom server-side built app to interface with the API, so this option is out for you.

What are you trying to do? What have you done?