Hello wei.w.he@liteon.com,
When you press the Refresh button, the options in the dropdown menu should add the board.

If not, then please go to Computer, and see the mounted devices. In my case, I have the S32K116EVB mounted on the drive letter D.

So, let the OpenSDA Drive Name selected on Custom and type the Custom OpenSDA Drive name the letter from the drive on which the board has been mounted.
Basically what the toolbox does is after the code has been compiled it copies the .mot file to the disk specified.
Another important thing that you should consider: Please discuss with your IT support to see that you have enough rights to use external USB devices.
Hope this helps,
Marius