ARK: Survival Evolved has been listed as part of Microsoft's new Play Anywhere initiative, which allows cross-buy and cross-platform play.
Players who buy the game on Xbox One or Windows 10 will get the game on both systems as part of Play Anywhere. The two platforms will share the same servers allowing for players on both PC and Xbox One to tame dinosaurs together in prehistoric harmony.
This system will only work with Windows 10 and not the Steam version of the game, which remains completely separate. It's not in place yet, and Studio Wildcard have yet to give any indication of when it Play Anywhere will be implemented.