Unfortunately Epic Games have blocked Fortnite on Paperspace cloud gaming machines.
We are working hard with them to resolve the issue, but for the mean time, you can play Fornite on AWS Cloud machines like the G2.2xLarge and G3.4xLarge.
If you want to swap to an Amazon machine do the following:
1) Click "Manage" under your existing Paperspace machine
2) Click "Delete" (this will clear all your existing save data and delete the hard drive of the cloud machine)
3) Click "Add computer"
4) Click "Rent a cloud computer from Parsec"
5) Select the AWS machine that you would like, in your region.
Your existing credit will transfer to the new machine
Please note that with AWS, you will be charged a full 1 hour fee every time you turn on your machine, even if it just stays on for 5 minutes.