The Creative toolset has different modes, or ways of doing things. Two primary modes used by Fortnite developers are Create mode and Play mode. You can only add things to your island from the Creative inventory when you’re in Create mode. When you first enter your island, you will be in Create mode. In this mode, you can access inventory items and island settings, you can place props and devices on the island, and you can customize devices.
Modifications you make are saved when you exit your island. In some cases, a device that you place on your island in Create mode will only function when you are in Play mode.