Can't I revamp our nonprofit website as a personal project?

Our nonprofit has a website. It was built via Dreamweaver by me (8-9 yrs ago), since I had no understanding of CSS and etc…
Can’t I revamp it as one of my projects?

As long as it fulfills the user stories of a project, I suppose you could.

How do I find out what are the requirements for projects?

You must run the tests associated with the project. Just add the following script to your project to be able to run the applicable tests.

https://cdn.freecodecamp.org/testable-projects-fcc/v1/bundle.js