I see.
Thats a Rx
In that case…
top right hand corner of the FC under the M3 Bolt.
The 3 Pins… J7 5V GND
GND - GND
VCC - 5V
I-BUS/S.BUS or PPM (Depending on which one you want) - J7 (PPM/SBUS)
That Rx will problemly have a breakout cable with it.