> I need the rendered content

what do you mean, here? you rasterize the markdown into an image?

[edit] yes he rasterizes the markdown into an image

Please read the README. The tool turns Markdown into NSPasteboard on Mac, or CF_HTML on Windows, so that when you press Cmd/Ctrl-P onto supported applications (Teams, Word, Google Docs), you get something similar to how Github would display the Markdown in the browser.