If you're wondering why Ms. McDougal didn't just publish her story elsewhere: the National Enquirer parent, American Media, could have sued to get their money back. McDougal took a $150,000 payment for her story, then the story was not published. Yes, McDougal could have presented her story elsewhere, but that's breach of contract. Even though the story was not published.
The problem, in simple terms: if stories are for sale, which they can be, then stories are shut down, it arguably amounts to hush money. These things aren't often revealed or judged against, from what I've noticed. There is no great judge of all news media that hands down fines. However, this time, it was seen as an attempt to affect an election outcome. That's what the FEC decided, and the agreement was for a fine in excess of $180,000.
Michael Cohen, Mr. Trump’s former attorney, said in a 2018 court hearing that he facilitated American Media’s payment to Ms. McDougal....
The May 17 agreement between A360 Media LLC and the FEC characterized the $150,000 payment to model Karen McDougal as an illegal corporate campaign contribution. Federal law prohibits companies from making contributions to candidate committees. ...
Paul S. Ryan, vice president of policy and litigation at Common Cause, expressed frustration that Mr. Trump has faced no repercussions for the hush money paid on his behalf. “The mastermind of this illegal operation has not been punished, has not been held accountable,” he said.
I don't know where the mastermind hat sits, but this arrangement clearly benefited the aspiring POTUS, who won in 2016. Then, lost his reelection bid in 2020.