I think what you are trying to ask is if you can develop your React app locally and just post a link to github.
Keep in mind that you are supposed to “submit the URL to your working project”. Github is not a working project, just a repo of code. One of the advantages of something like Codepen (or another online IDE) is that it is both.
That being said, it is fine if you want to build locally but then you’ll have to find somewhere to host it. You could host your apps on gitpages or something like that. You could put a link in the app that points back to your git repo, if you want.