How do I connect my iPad 9th Gen to a 4-usb port hub?

Hello Jerrie257,

The iPad 9th Generation connects through the lighting port on the device. That is the only way, to the best of my knowledge I believe so. If your 4-USB port hub doesn’t use lighting to use it, you may need an adapter.

Hope I can help!

Connection of external storage devices is possible - with some caveats...

To be recognised by iPadOS, the attached USB storage device must be formatted to FAT, FAT32, exFAT or APFS with a single partition. As the iPad has limited power capabilities, dependent upon the Storage Device, an external power source is often required.

If your iPad Pro has a Lightning port, you will need to use an Apple Lightning to USB3 Camera Adapter to directly connect USB devices to the iPad:

https://store.apple.com/xc/product/MK0W2ZM/A

This adapter has both a USB 3.0 Type-A connector and an additional Lightning port to supply power, from your charger, to both the iPad and connected device. The external charger must be rated at 12W or more.

If you have one of the newest iPad Pro models, with a USB-C connector, you may need to utilise a powered USB hub (i.e., it has its own source of power) - connecting both the iPad Pro and the storage device to ports on the hub.

Some additional information can be found here:

Connect external devices or servers with Files on iPhone - Apple Support

https://www.imore.com/how-use-external-hard-drives-your-iphone-or-ipad