[XCSme]

I think the problem is simply that the author misinterpreted the term "conversion". A conversion is not an app install, is a successful pre-registration.

Now, it seems like there is a 10% conversion rate from the pre-registration to the installation of the app. Why that is there? That's a different question, and probably explained by their docs regarding pre-registration and what it actually means.

$10-$15 for an app install is probably pretty normal.