Copy Pictures from PC (Win 10) to iPad Pro

Direct transfer of photos is disabled when iCloud Photos is turned on, on the target device.

You can turn off iCloud Photos on the iPad in Settings ➜ Photos, or use the iCloud Photos app in iCloud.com or through iCloud for Windows in the Windows Explorer to transfer the photos.

If and when you turn off iCloud Photos the Photos section there will then be enabled and let you directly transfer photos by synchronizing the iPad to the computer.

To transfer or synchronise photos between your PC and iPad, by far the simplest and straightforward method is to install and use iCloud for Windows.

iCloud for Windows will allow you to simply share and transfer your photos between iPad and PC via iCloud - without any wired connection:

Download iCloud for Windows – Apple Support

Set up and use iCloud for Windows – Apple Support

Alternatively (as you already appear to have done - and suggest that you prefer), you can install iTunes for Windows on your PC. This provides other transfer and management options - but only via a cabled connection between the iPad and computer:

Download and use iTunes 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.

If you haven’t actually installed and tried iCloud for Windows, I strongly recommend that you give it a try. You may be very surprised at its usefulness and simplicity.