Ensure the Huawei mobile partner drivers are installed so the PC recognizes the COM port.
Using third-party unlocking software comes with significant caveats. Since this is not an official Huawei product, keep the following in mind: huawei modem unlocker v5.7.7
Run the tool as Administrator. Click "Refresh" or "Detect" to find your device. Ensure the Huawei mobile partner drivers are installed