Fortnite say I need a 2 GB to play and I have a 32GB It will not let me play

Do you have a 32GB iPhone or 32GB available? Go to Settings > General > About and check Available and make sure you have at least 2GB available. However, realistically you will need more than 2GB just so your other apps can run.

Talk to the app developer. That's not an Apple product.

According to the Apple App Store, Fortnite for iOS only requires about 155 Megabytes of storage (note you posted your issue in the iPhone forum).

Fortnite by Epic Games

https://itunes.apple.com/us/app/fortnite/id1261357853?mt=8

Fortnite for Windows or Mac OS requires 4GB of RAM and 8 is recommended. But you cannot run that on iOS of course. It also looks like Fortnite on Mac OS is notoriously buggy and the developer doesn’t seem interested in addressing issues with Mac OS.