It's buy to play, then there's an optional subscription model which gives you DLC access for as long as you stay subscribed, and a monthly income of coins. You can use the coins to buy cosmetics, as well as the DLC which will stay active without a subscription if bought via this method. You can also buy coins in the store for RL money. For a free to play model, it's pretty good. You don't 'need' to subscribe or buy coins, 90% of the store is cosmetic/mounts, etc.