Perhaps the easiest method to transfer files between your PC and your iPad is to install iCloud for Windows on your PC. This can be downloaded (for free) directly from Apple - or for Windows 10, from the Microsoft App Store.
Set up and use iCloud for Windows – Apple Support
Download iCloud for Windows – Apple Support
If using USB storage, to be recognised by iPadOS, the attached USB storage device must be formatted to FAT, FAT32, exFAT, APFS or HFS+ with a single partition. Microsoft NTFS and other proprietary device formatting are not supported.
More information about connection to external devices and storage can be found in the iPad User Guide - along with other frequently overlooked information about your iPad and iPadOS:
Connect external storage devices to iPad - Apple Support