Open your printer.cfg file in whatever editor you feel comfortable with. My preference is to use nano via a SSH terminal, but if you prefer to use WinSCP you're welcome to do so.

In the section [mcu] on the line starting "serial:", copy the path you copied to your notepad for the X/Y/E controller.

Be sure you have the whole path as outputted by the terminal. It requires /dev/serial/by-id/ at the start.