Fair Use, Copyright and Donations

I don’t know which applies more here Fair Use or Copyright so I put both.

Do Donations break copyright?

As in, if I haven’t gotten permission from the copyright holder, but I want to make a fan fiction (Short Stories posted for free on social media platforms such as Reddit, but not published), will I be allowed to so, or is it illegal?

Continuing, if I accept donations, but not as a form of payment for the series (ie. Not locked behind a paywall, still 100% Free), but just to help continue the series, solely should people want to help it continue, is that illegal?

Edit: Location is Florida, United States