This article explains how to connect a wired keyboard to an iPad using a Lightning to USB (or USB-C to USB) Camera Adapter. It includes information about other devices that can connect to the iPad.
How to Connect a Keyboard and Mouse to the iPad Pro [Wired/Wireless]
When Apple switched from the old 30-pin connector to the thinner Lightning connector, it changed the name of the Camera Connection Kit to the Lightning to USB Camera Adapter. While it has the word “Camera” on it, the adapter essentially adds a USB port to the iPad. Many newer iPad models also include USB-C connector ports, and can use USB-C to USB adapters instead of Lightning to USB.
A USB port requires two things: a device such as a wired keyboard, and a compatible host device. In this case, that host device is the iPad. The order in which you connect your iPad, adapter, and keyboard can affect whether the devices work together.
Connect the Lightning to USB Camera Adapter or the USB-C to USB Camera Adapter to your iPad.
