I don’t see any Postparty prompts to clip after an elimination or Victory Royale in Fortnite
If you do not see any prompts, make sure you have logged into the Postparty app with the same Epic Games account you use to play Fortnite. When you first log into the app, it should show you your Epic username in the header, and your console usernames (if you have any) in a window at the top of your Library. You can double-check in game by looking under the Account tab in Settings.
If you only see the prompts sometimes, there is a cooldown period after one prompt before another will pop up. Because of that, you may not always see a prompt if you get multiple eliminations quickly. You can still take a clip at any time during the match or on the Victory Royale screen by holding the clipping button, even if the prompt isn’t on screen.