Error CMD must be involved in the root of workplace

Hello I am using Ubuntu version 20.04 NOT WINDOWS

I want to run the comments given in this GitHub: https://github.com/radar-lab/ti_mmwave_rospkg

In cmd, I want to run codes from step 3-8, I am stuck in step four as it gives this error:enter image description here

I am successfully able to run step- 3 but step 4 gives this error. please tell me why it is giving this error