Problem in configuring busybox (for generating root file system for DE10 Nano embedded linux) as per step 7.2 of this tutorial -

Hello everyone,

I am trying to implement the tutorial on the above website for the DE10 Nano board. I am implementing it on Ubuntu 16.04. However, I am getting an error in step 7.2. When I run the command as given in the tutorial i.e. ( make -C buildroot busybox-menuconfig ) the busy box settings open up as shown in the image in step7.2 of the tutorial.
Then when I save the default settings as mentioned in the tutorial , the settings get closed and at the end of the terminal I get the following error message as shown below ( Error message - No such file or directory)

Can anyone please help me solve this error ?
Any help is appreciated

Thanks and Regards