iPad cannot restore from local backup

Your backup does not contain the code for third party apps. (It does contain your personal data associated with these apps.)

Third party apps must be re-downloaded from the App Store. This process takes place automatically when you restore a backup. But clearly it requires connection to the internet. It also requires the apps to still be available in the App Store (not obsolete).

To further clarify, while App-data is included within your backup, Apps themselves are not included within the device backup.

For Apps, the backup process creates a record of the Apps that are installed on the source iPad - and it is this record of installed Apps that is restored to the target device along with associated App-data. For Apps that are still available for download from the App Store, the corresponding Apps are automatically re-downloaded and installed from the App Store.

Not all Apps will, necessarily, continue to be available. Apps may have been removed or retired from the App Store by the respective App Developer.

This might suggest that your backup was incomplete - or was not configured to back-up your third-party Apps. If applicable, your App-data may be irretrievably lost.

While too late for this occurrence, if your data is critical it is considered good practice to have at least two (ideally three) backups - using two different backup types. Backing-up to iCloud is fully automatic, whereas backing-up to a Mac or Windows PC is a manual process. Using both provides a safety-net; if one backup is incomplete, you can try to restore the alternative backup.

This support page outlines the natively supported backup methods for iPad and iPhone:

How to back up your iPhone, iPad, and iPod touch - Apple Support