The "validation" refers to the digital signature required to run the app on iOS.
Ensure iTunes is updated, as 3uTools relies on Apple's drivers to communicate with the device. If the validation fails while downloading firmware: 3utools installation package validation failed
: If the drive where you are installing 3uTools is nearly full, the installer may fail to unpack or validate temporary files. Third-Party Firewall Blocks The "validation" refers to the digital signature required