February 17, 2016
The popup windows in both Kim Kardashian: Hollywood and Kendall & Kylie explaining the Krossover event are temporary (they show for each player for 24h after he/she first sees them) but the ability to claim the rewards is perpetual. Once a player on either game initiates the Krossover event, he/she has unlimited time to claim the rewards.
There are 2 possible ways with which you can complete this quest, depending on the game which you logged in first. But to ensure that you have completed the quest, please make sure that you are level 7 or higher in Kim Kardashian: Hollywood and level 8 or higher in Kendall and Kylie.
Once you have achieved these requirements, you get an instant pop-up in Kendall and Kylie informing you that you have completed the Krossover Event and you have successfully received the rewards. Then please go to wardrobe and scroll down completely to find your reward items in Kendall and Kylie.