When I plug in usb-c into my iPad Pro it does not activate a thumb drive. What do I have to do to get it to work?

Hello Chessproblem507,

Thanks for asking the Apple Support Communities for help with using an external thumb drive with your iPad Pro.

Please start by verifying everything is set up as described here: Connect external devices or servers with Files on iPad - Apple Support

This article also has screenshots and more info: Charge and connect with the USB-C port on iPad Pro - Apple Support

If you are using this adaptor, please check this help article: About the Apple USB-C Digital AV Multiport Adapter - Apple Support

Thanks and have a wonderful day.