DWM3001CDK DW3_QM33_SDK and the UART command

The manual says:

To set UART communication status, use “UART ”,
• where value:
– 0: disables communication using UART,
– 1: enables

with the note

Note: The “UART” command is not available when the compile flag “USB_ENABLE” was removed from the project.

I finally got the project to compile and found the .hex file. I first tried the CLI version. Worked fine, got two red and one green LEDs, and it measures distance ok.
How do I turn on the UART command, and what precisely does it do? I was rather hoping that it would let me type in one terminal and receive the text on the other.
I tried removing the ‘D’ from the "CMAKE_CUSTOM_C_FLAGS " line in “project_common.cmake” and the unit no longer worked at all. Only one red blinking LED and no command menu.