This is a private beta, so you can get access one of two ways. The first is to simply pre-order the game. Digital pre-orders will be granted access automatically without a key. You can also use manual links to add it to your library on Xbox One or PS4. Retail pre-orders will come with a unique code to be redeemed through the official site, which will then grant you a key. Note that digital pre-orders through the Epic Games Store will have their keys delivered in an email from Epic.
The other method of entry is to sign up through the official site and hope to be randomly selected. If you are, you'll receive an access key via email, and then redeem it through the same method as the pre-order.
The beta will include two main missions, five side missions, and other open-world activities. You can also dive into one of the three new Dark Zones. An Invaded mission, a piece of endgame content, will unlock on February 8 at 1 AM PT / 4 AM ET / 4 PM GMT. Players will be capped at level 30.