Hey,
Sorry about this not being clear enough on the website, it should have been more precise and better formulated. The blog/in-game article says "Magic Coins to giveaway to the Community by the Captains".
During the event, all crowns won by each member of your team in the challenges and on the ladder will be added to that achievement. Each tier (the first on being 5000 crowns) will unlock 1 Crown on the website, which will unlock Magic Coins for the Captains that they will give away to the Community. In total, 3 Crowns can be unlocked, so 3 "rounds" of Magic Coins.
Not all players will receive Magic Coins automatically.