The game is entirely free-to-play, with all content accessible to players who don’t want to spend anything. However, as to other similar “freemium” business models of today’s games, players who can afford to spend are treated with lots of optional yet convenient time-saver consumables, items, and access to cosmetics such as Costumes, Mounts, Wings, etc.
2. If you can afford to spend a bit, the game is generous enough to give you really useful and permanent benefits and boosts that will make your progress a lot faster.