As of September 26th, 2017, the Battle Royale mode is Free-to-Play for ALL players.
How to Download
On Playstation 4 and Xbox One, navigate to the console's respective digital storefront and search for "Fortnite Battle Royale".
On PC/Mac, download and Install the Epic Games launcher by clicking your platform Here. Once installed, log into the Epic Games launcher using this email address and whatever password associated with your Epic Games account. You can then install the game from the "Fortnite" tab on the launcher.
If you are interested in additional. details about Fortnite Battle Royale, check out this Announcement Post on our Fortnite News Blog!