This does not mean that you must play your next match within 48 hours. It simply means that your next match must be in the schedule within 48 hours of knowing your next opponent.
Crash means a player cannot reasonably be expected to play the game any more. This is the especially the case if the game suddenly closes itself. But also if repeated Hitman server disconnects occur, the game is stuck in a loading action (possibly infinitely), the player's stream or internet is cutting out for an extended period of time, or the player experiences a significant and persistent drop in FPS to unplayable levels.