We have served their ads for weeks and they have not paid even a dime.
They provided us with faulty traffic data which asserted that their ad code was only appearing on a limited amount of our old articles.
After we sent them a screenshot which proved that to be erroneous they then ask to test our ad code on a different site again without prepayment.
This is the typical action of scammers.
They promise you a pay-out based upon traffic targets. They then cheat you by claiming traffic must less then they actually received. They then make promises to pay you if you get the traffic they want on a different site you have.
They eventually paid 1.50 euros which only covers a tiny fraction of the traffic they received. This doesn't even cover the work putting up their ad code.
It's our professional opinion that this company acts consistent with scammers.
Protect your websites from scamming by demanding that the ad network pay a deposit before serving their ads.