A prompt to "sign in" or "create a Google account" is common for T-mobile handsets.
If this message is displayed on your handset instead of a prompt to enter the unlock code, you need to activate the phone with Google. A T-Mobile SIM card is required to do this, but only for activation. Once the phone is activated with Google, power off your phone, insert the SIM card that you would like to use and power the phone on. You will now be prompted to enter the unlock code that we provided you.