Connect device to PC, if it does not have COM ports like in the image below, follow the rest of the procedure

Launch DC-Unlocker client software

Select manufacturer: ZTE modems, model leave Auto detect (recommended).

Press "Detect" button (Big magnifying glass)

DC-Unlocker software will enable COM ports automatically of your device during detection

Modem will be detected afterwards

If you get warning window during detection, run DC-unlocker as administrator and repeat the process