Affiliate Marketing Expert

I have a science website
(mysteriousofscience.com) I started to promote online courses on my website by publishing a review article about a course targeting college students and researchers.
I tried to promote the product via native ads but I couldn't get any sales.
I need help from professionals to get more sales and raise ROI %.
My method is to put the affiliate link in the review article and promote the article to get sales.
I work with Admitad affiliate company.