Michael Cohen outlined a crime. Did he prove that Trump committed one?

The most an American is allowed to contribute to a presidential (or any other federal) campaign is $3,300. The intent of this limit is, in part, to prevent campaigns from taking huge amounts of money from individuals to whom the candidate might feel beholden. Contributions and spending are reported so that the public can see both who is funding campaigns and how the money is being spent. All of this is outlined under federal law.