IMHO they are looking on trading volumes and rare tokens that you trade. As I remember coin will add on CMC after 50000 USD day trading volume.
They removed the exchange volume requirement a while back.
https://in.finance.yahoo.com/amphtml/news/coinmarketcap-removes-volume-requirements-cryptocurrency-192959566.html
Coingecko is far better than cmc tbh, they have excellent customer support which I adore the most about them.
Good to know, I will contact them to list our exchange there too
