Codepen not working with React

Hi all!
I am trying to test my Markdown Previewer project on Codepen, I wrote originally on my text editor, forked the Pen they suggested, have tried to add code in different wats and nothing happens, I can’t see my app.

Any clues as of what might be causing the issue?

Here is my pen link–>

let marked = require("marked");

IDK about the first error but the 2nd indicates that this line is trying to execute on a NodeJS environment. Codepen doesn’t have a node runtime for you to import modules like Marked, you have to import the library from a CDN as a .js or .min.js.