Launch DC-Unlocker client software
Open Server tab, enter your username and password that you received after credits purchase. Click "Check login". (you can buy credits here www.dc-unlocker.com/buy).
If DC-Unlocker/Vygis/Rocker/Infinity dongle is connected, do not enter username and password, only click "Check login"
Select manufacturer: ZTE modems, model leave Auto detect (recommended).
Press "Detect" button (Big magnifying glass)
Wait till DC-Unlocker fully detects device
If you get "modem not found" error message, check in device manager if R206-Z is correctly installed. "?" or "!" marks next to lines that belongs to your device means drivers are missing for it. ZTE R206-Z Drivers download here
If Warning box pops up during detection run DC-Unlocker as Administrator and perform detection again.
Right click on DC-Unlocker icon and select "Run as.." or "Run as administrator" from options menu to launch software with administrator rights
Open Unlocking tab, click Unlock
Wait till you see a message that modem is unlocked
After you see that modem was successfully unlocked, restart it by disconnecting and connecting back. Only then you can use it with any SIM card