I am trying to get the backup from my old iPhone that was destroyed

Restore your device from a backup on your computer

1. On a Mac with macOS Catalina 10.15 or later, open Finder. On a Mac with macOS Mojave 10.14 or earlier, or on a PC, open iTunes.
2. Connect your device to your computer with a USB cable.* If a message asks for your device passcode or to Trust This Computer, follow the onscreen steps. If you forgot your passcode, get help.
3. Select your iPhone, iPad, or iPod touch when it appears in the Finder window or iTunes. If your device doesn't appear, learn what to do.
4. 
5. Select Restore Backup. If a message says that your device's software is too old, learn what to do. 
6. Look at the date of each backup and pick the most relevant.
7. Click Restore and wait for the restore time to finish. If asked, enter the password for your encrypted backup.
8. 
9. Keep your device connected after it restarts and wait for it to sync with your computer. You can disconnect after the sync finishes.
10. Get help restoring from a backup.

You are not being clear. Do you want to access you iCloud backup using your HP, or do you have a backup stored on your HP via iTunes?

If the latter follow SravanKrA instructions in his post. You would still need an iOS device to access and restore the backup

If your backup is on iCloud, you cannot use computer to access it; you would need an iOS device to restore.