Unable to install this update in ipad pro 2020

It is possible that your WiFi router is unexpectedly blocking access to some internet/server resources - which might be resolved by a restart of your router.

To restart you home router, disconnect power - then wait at least 30 seconds before restarting. When you router has rebooted (which may take several minutes), force-restart your iPad:

• On an iPad with a Home button: Press and hold the top button and the Home button at the same time. When the Apple logo appears, release both buttons.
• On an iPad with Face ID: Press and quickly release the volume up button, press and quickly release the volume down button, then press and hold the top button. When the Apple logo appears, release the button.

What happens when you try?

You need an WIFI network connection, not personal hotspot.

If you don't have one, borrow it from a friend, or ask for help at an Apple STore or authorized Service provider.

Regards

Giulio