As Emmet said, if you pre-purchased it then you'll get both games, they let their player base know this and even offered the game on sale (17 Euro) before the split so people could get both survival and battle royal! There's a method behind it though, separate login servers, authentication, developement etc etc. Game statistics showed that there's a large base of players who either just play one or the other, with a small player base playing both in a given sitting and if there was a problem with say the battle royal servers then that would drag the survival servers down with it. The knock on affect was ridiculous!
The only downside to the game splitting is the extra few quid needed to play both, without the split battle royal wouldn't have the capacity to add new maps offer better performance and features that has increased the appeal ten folds for me.