I had to dig through the schematics PDF since I didn’t find it anywhere else.
CN10 (four pin header next to the LEDs) is, in order from farthest to closest to the LEDs:
+3V3, UART0_RXD_D, UART0_TXD_D, GND
So hook up your TX to pin 2, RX to pin 3, and ground to pin 4. I was able to connect with 115200 8n1 no flow control.