! The steps listed in that repo are for meant for development of the Prefect UI.
Instead you should take a look at Prefect Server (the self-hosted orchestration stack that you'll need to deploy either locally or to your own cloud servers somewhere) or Prefect Cloud (a Prefect-hosted stack that doesn't require any additional setup outside of what you already have). You can find some information on both here
I'd personally recommend signing up for Prefect Cloud
; the amount of work required is far lower than deploying your own stack and it has the benefit of being fully managed by the Prefect team, which means the API and UI are always up to date and all you need to manage are your own execution environments and code. Oh and it's free!