difference between 2 popunder types

[deppstar]

Hi, an offer has the attached limitations for allowed traffic; the question is what's the difference between a CLICKUNDER/POPUNDER (red flag) and a POPUNDER/AFFIRMATIVE CLICK VIA PRELANDING? I see several traffic for the offer coming from simple popunders so what's the "trick" here to comply with rules? Using some kind of redirection so that popunder is not associated with the offer directly or the like ? Tx