Hello @javenhuang1998,
On our side we obtain the following:

[Running the usb_device_cdc_vcom example]
Is this what you are looking for? If so, could you please test the example following the next steps?
- Open MCUXpresso IDE v11.8.0 and the usb_device_cdc_vcom example,
- Connect your LPC55S16EVK board to the computer through J1 (JLINK2) port,
- Debug the program,
- After it hits the breakpoint, click Run,
- Connect the J3 (FS_USB) port to the computer (which will be numerated as COM Port) and,
- Launch the terminal. You might be able to send information which will echo and displayed in the terminal.
Best regards, Raul.