Question about cpa offers

Hi Guys, i'm new on the cpa marketing and i would to know something please, let's take an example:
There are some offers in a cpa company like Mobile Pin Submits (user has to add his phone to complete the offer)
One of this offer has no details, it's just a download button like "your download is ready, put your phone to access it"
What i woud like to know is, how do we know the market of an offer like that?
I could use this offer in any kind of websites but if the user is completing the offer and if he's not getting what he saw on the site, he will never come back?
Thank you