This does not mean that the match must be played within 48 hours. It simply means that the match info must be sent to an admin to be scheduled within 48 hours of being matched against an opponent.
A "crash" means that a participant cannot reasonably be expected to continue playing the game. This is the especially the case if the game suddenly closes itself. If there are repeated HITMAN server disconnects, the game is stuck in a loading action (possibly infinitely), the participants'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 an extreme degree, the match admin will treat any time spent returning the game to a playable state as "crash time".