I want to ask this:
"Will ad business comply with GDPR law. If yes how?".
Where should I ask this question? It seems related to both business model and law?
I'd err toward Law because it's a legal requirement in certain countries. You'll need to be pretty specific about your request however as there's plenty of resources about GDPR on the internet in general, so you need to demonstrate in what way that information wasn't suitable for you.
As always, search before asking as GDPR is a common topic and your question (or something very similar) has probably been asked about before.