Michigan is asking to upload an artifact that demonstrates your learning in action. If I plan to attach a link to my non-profit organization’s Instagram page that focuses on sustainability, do you think it would be a good artifact? The non-profit organization basically raises funds and creates events relating to sustainability.
Have you seen this:
https://michiganross.umich.edu/programs/bba/admissions-blog/2017/11/27/here-are-our-favorite-portfolio-artifacts-ross-applicants
Not sure if you want a link or a specific message on the page, but it sounds like it meets their criteria. If they give you a little space to explain, maybe you could lay out the non-profit in a few sentences. If by “my” you mean you started it, you might want them to know that also. But if you already talked about it in other essays, then you may want to look for something else you can help them learn about you.
Best of luck!