It depends on your licence and local law - target only markets where you're legally permitted to operate and advertise. With Cointraffic, if your gambling licence covers specific territories, your campaign runs in those territories only.
A few markets are also restricted on certain premium sites - for example, Singapore, Malaysia and Vietnam for gambling on some explorer and data sites. Use GEO targeting to run separate campaigns per market and control bids; your manager can group your best-performing countries.
Confirm licensing per market with your legal team - general information, not legal advice.