Well, the 99 USD price is kinda a message saying "DO NOT BUY THIS COURSE"
Given that everything is free, the course is a nice way to test your common sense with 30 quiz questions (in total, entire course has 30 quiz questions).
Adding the certificate, makes no sense, absolutely none. The quizzes were extremely trivial, high-school-math like, extremely intuitive and common-sense. Yet, it is priced at 99USD, a ridiculous price.
You look over to Analytics edge, with 20+ hours per week worth of workload and challenging assignments, with the same certificate price, the pricing just makes no sense whatsoever.
Don't buy this course, I regard this as a "do for fun" course, you won't gain any technical expertise or compentency in this course.