How can I transfer files from a Zip drive to my iPad?

Presumably you refer to an Iomega Zip Drive? If so, these are very old (long obsolete) technology. As these drives require installation of device-driver software, they are not supported by iPadOS.

To transfer data/files from an Iomega Zip drive of any type to your iPad, you will need to connect the Zip drive to a compatible Windows PC - and first transfer the data to USB storage (such as a USB Thumb Drive, flash drive, or similar) - or transfer to cloud storage (e.g., iCloud) where it can be accessed by your iPad.

To synchronise or transfer files directly between iPad and a Windows PC, you will need to install the most recent version of iTunes for Windows:

Download and use iTunes for Windows – Apple Support

Update to the latest version of iTunes – Apple Support

If you simply wish to exchange files and photos with the iPad from the Windows PC, you might instead consider using iCloud for Windows. When signed-in with the same AppleID, you can simply use iCloud to exchange or synchronise files:

iCloud for Windows

Download iCloud for Windows – Apple Support

Set up and use iCloud for Windows – Apple Support

You can install and use both on the PC. They will happily coexist - and provide considerable flexibility in how you move/share/transfer photos and other documents and data between iPad, iPhone and your PC.