I could be wrong, but I think that it could be your graphic or your link. Your graphic says "free course," but the pin description clearly shows that the course is 39.99. I know that you have a free option as well, but something to keep in mind.
Also, when your ad gets rejected, you would have received the reason so that you know what you need to fix/ work on.
I hope this helps.
Owner @Debbie Roy Media Pinterest Strategist & Coach for Entrepreneurs