Can someone tell me if I need to purchase the online subscription in order to download and play Fortnite on Xbox? It's for my children. I will purchase either the XBOX or PS4. Also am I capable of putting this on a laptop or Chromebook?
You need an Xbox Live Gold subscription while not needing a Playstation Plus or Nintendo Switch Online subscription.
The source is right here: Epic Games FAQ
(The answers on are the 2,3,4 Q/A)
To answer your other question, you can play Fortnite: Battle Royale (And Save the World) on a laptop, or any other PC but you need to make sure it is compatible with so.