Advertises have access to Affle's tools, as well as their own (such as Appsflyer) to figure out where a user is coming from.
There are quite a few privacy concerns. Affle has cross-advertiser information, so they know who's a more likely customer for another advertiser. Apart from having a fair guess of a user's age-range, preferences, etc.
But India doesn't have a privacy law yet. In EU, where GDPR is already in place, ad tech firms are navigating through a minefield. Affle, on the other hand, is in markets with little to no privacy legislation.