I have a Nokia 7 and used the Unlock tool. I get the following: Starting the bootloader unlock process... Info: I will switch the slot after finishing the unlock. Looking for a fastboot device... A fastboot device detected! Collecting device details...
Device Details Serial number: C1NGA1E7A2324849 Bootloader unlocked: False Bootloader Critical Unlocked: False Project code: C1N1
Info: The connected device is supported by the unlock tool. Starting bootloader unlock process... Warning: Do not disconnect the smartphone unless instructed. Info: Bootloader type is: commercial Collecting data to flash service bootloader image... Device challenge: 68E6ED4A285687167A431D94BDAE8F6F7721E561 Connecting to the server for response... Solution received and saved to veracity.bin Flashing the solution to the device Flashing C1N-abl_service.elf to abl Flashing C1N-abl_service.elf to xbl Rebooting to bootloader... Info: Bootloader is now service. Proceeding... UID challenge: 0FCACFE4AE5FD62266E11189A57F73432527013C Connecting to the server for response... Solution received and saved to UID-C1NGA1E7A2324849.bin Starting the unlock flow... Error: Auth key verification failed. Try again or contact admins.
The key was valid and generated a few minutes before running the tool.