The software was downloaded and when is time to install it says error
device says there is an error installing software
Unable to install software
iPad Pro 12.9-inch, 3rd Gen, Wi-Fi, Cell
Try deleting the software and start again.
Go to settings>General>iPad Storage. Let the list of apps load. Swipe to find the downloaded iOS software. Tap on it. Delete it in the next screen. Restart your iPad. Then go back to Settings>General>Software Update and start over, download and install again.