Even paid unlock services use remote dongles – they own the hardware and charge $10–$15 per code. The “link” they send you is just a remote desktop session.
Thus, if you search for “zte z320 unlock nck dongle link,” you are likely looking for either:
He clicked the Z320 into the micro-USB cable, the connection firm. On his monitor, the NCK software interface sprang to life—a grid of clinical buttons and progress bars. He selected the 'ZTE' tab and scrolled until he found the Z320 profile