What this means is that Windows 10 Store players will be isolated from other PC versions of the game, there will be no cross-play multiplayer support.
As Windows Central reports, it's unclear why Activision made this weird decision because there's nothing about the UWP toolset that prevents cross-play between devices and platforms.
A source familiar to the matter recently informed us that the decision to segregate Windows 10 Store and Win32 PC platform players is entirely on Activision. There is nothing about the UWP toolset that prevents cross-play functionality, as seen with CD Projekt RED's upcoming GWENT card game.