Since Android™ 5.0, the device is linked to a Google™ account for security measure. Thus, if the device is lost or stolen, the login and the password will be required to pass through the wizard once the device is restored from the recovery menu or the Android device manager.
If you are the device's owner, you have to set the same Google™ account that you have filled in the last wizard.
If you have bought the device second-hand, you may have to contact the previous owner to unlock it. Once the device is unlocked, we recommend to perform a factory data reset from Android™ in order to let you set your own Google™ account.