https://www.polygon.com/2018/3/15/17126798/fortnite-battle-royale-mobile-invite-ios-epic-games-app-store-first-wave

The first wave of invites for the mobile version of Epic Games’ Fortnite is going out to players who signed up to test the game. Players who have been selected should have an email from Epic inviting them to download the game from Apple’s App Store.

Epic said on its website that this is merely the “first round of invites for the Fortnite Invite Event on iOS.” The company said it will send out additional invites to players “in the coming days and weeks, so if you don’t get one right away, don’t worry.” Players can still register for an invite at the Fortnite website.