It sounds like you’ve created a fork of a repository that is published with GitHub Pages, but your fork is not yet being published.
If that’s right, it’s most likely becuase GitHub Pages has yet to be enabled on your fork. GitHub Pages is not enabled by default on new forks, even if it was enabled on the fork’s parent.
To enable GitHub Pages, you’ll need to set a publishing source from your fork’s settings tab. This help article explains the process in more detail:
Once that’s done, your site should be published at https://primetime5502.github.io/CityGuesser within about 10 minutes. If it still isn’t showing up after that time, you might need to clear your browser’s cache.
I hope that helps! Good luck for your Hackathon!