How to use RS232 port in Delta?

I am using LattePanda 3 Delta.

For RS232 communication, I wired as follows according to the manual.

But I don't see 'COM1' port in windows.

I tested it by connecting to 'COM4', but I couldn't send or receive any data.

I searched the forum and found a post saying to use "RS232 to TTL Converter".

( https://www.lattepanda.com/forum/topic/315352 )
 

Is "RS232 to TTL Converter" mandatory?

Or are there more actions I need to take?