AppCoiner claims it is an easy way for you to make money by testing apps and giving feedback about them through writing short reviews.
AppCoiner has several warning signs including the fact that you are not told there will be a price to join, until after you have given your email to join.
You will only get paid, if people come to the site. And you would need a lot of traffic coming to that site to make any real money.
And traffic is not so easy to get. It takes a lot of time and effort or a big budget, and you are told nothing about this before you join.
This is nothing at all like getting paid for giving feedback on for example survey sites, and it is not at all what you are told before joining.