How to transfer files from CD/DVD onto iPad Pro?

There’s no native way read a digital disc on an iPad, and I don’t think a 3rd party manufacturer makes such a solution.

You will need to extract these files from the discs on a computer, macOS or Windows, then upload them to whatever cloud service you’re using to make them available on the Internet to your iPad. If you don’t have a cloud service, iCloud is one option, as nohillside mentions above, but there are others such as Dropbox or Google Drive. Dropbox and Drive have iOS apps to handle file transfers. I use all three cloud services on my iOS and macOS devices.

_{Disclaimer: I am not an employee of Apple, Dropbox nor Google.}

I tried connecting a DVD drive to my iPhone 8 by an Apple Lightning to USB 3 Camera Adapter and I was not successful in reading any discs. The adapter does work with the USB 3 flash drive I tried to make sure I didn't have a hardware failure elsewhere.

This was with an iPhone 8 and not an iPad Pro so perhaps not a valid test. The iPad Pro is more "computer like" than the iPhone and so might support a DVD drive plugged into it. If you have any USB DVD drives around then it doesn't hurt to try it. Be aware that USB powered DVD drives are very picky about the ports they plug into, they take a lot of power and not all hubs or adapters will provide the power they need. Use a drive that takes power from somewhere other than USB if you can.

If plugging in a DVD drive into the iPad does not work then you'll need something to be an intermediary. An Apple computer with a DVD drive might work best as that means you can use AirDrop and not have to copy the files to some place in the middle. Using a flash drive should work, copy the files off the DVD onto the flash drive with a computer and then move the flash drive to the iPad to copy them off there. Copying the files to iCloud, Google Drive, DropBox, or other internet file service, as mentioned by other commenters, can work too. If you have an AirPort, Time Capsule, or other similar file sharing capable wireless access point, then you should be able to share a flash drive or something to copy the files over.

If the files are not too big then maybe e-mail them to yourself and pick them out of the e-mail on your iPad. That's appears to be a fairly common practice I've seen people use.

There's a lot of ways to try. Good luck.