How to communicate UART on rak5010 using RUI compiler online?

Hi everybody!
I am trying to communicate rak5010 with another microcontroller using UART communication. I want to use RUI compiler online to do that. I looked at the rui.h file and saw some UART configuration functions but there is no specific instruction for configuring the TX-RX pin.
Is it possible that I want to configure the NRF_IO2 and NRF_IO3 pins to TX-RX for UART communication with another microcontroller?