With 78M daily volume the exchange should be listed in Coinmarketcap, but it's not.
I'm sticking to exchanges listed in CMC for two reasons: I can make a cross-reference of the traded pair and the exchange have some reputation. Until I see it in CMC, I doesn't have a reason to try it.
Indeed, PrimeXBT offers aggregated liquidity from 12 exchanges, it's not a local volume. otherwise it would be impossible for a new exchange that just launched a month ago to has that huge liquidity. It's not clear yet if they have a legal agreement with those platforms or they just use API on their side since there is no partnership on the website. PrimeXBT claims to bring aggregation that used at Forex for long time to crypto space, however gaining reputation is a long journey.