Tweak and add new functutionalities to working REACT app

I have a Python/REACT app working online and I need minor tweaks to it and to add the following functionalities:
1. Add user management to the basic one that exists now. Registration approval, create, edit etc.
2. Add an API for access by authorized users

TWEAKS:
Simple correction of text and image display. Add values to current graph.

Access to code and additional information is available.

Only apply if you provide regular updates please.

Also note, the original app cost less than $200 to build by a PPH freelancer.