I have no difficulty helping you.
We changed your goods to RS485 interface for you before shipping according to your needs.
But the adapter board is the default configuration USB-RS232 in the kit. as you said, this should be the reason why it can’t communicate.
If you just want to test you can change the LCD to RS232 communication and we will send you free USB-485 adapter board with your next order since we do not have them in stock for now.
If you agree to change the interface, then please let me know and I will show you how to modify the resistor.