Oh, Linda. If only you met me sooner. Everything you need to know about writing on Medium can be found for free. I learned the hard way many years ago paying big bucks to attend writing conferences that these courses are mostly filler and promotion for other products.
The real danger, however, is that courses and seminars feed procrastination. You only become a writer by writing, but writing is hard. So we take a course to fool ourselves into thinking we’re making progress. “I’m taking a very expensive course by a top writer!”
Does Stephen King hawk an online writing course? No because he makes millions writing books, movies, and TV shows. People far less talented end up selling courses because conning newbies is the only thing they’re good at. I can probably name all three of the people who conned you. After you’ve been here a year, you figure out who they all are.