From the image this appears to be a view into the socket on the transceiver side.
Based on the above RJ-45 mic pinout Digirig audio cable will look like this:
RJ-45 Pin #1 (GND) → 3.5mm TRRS sleeve (GND)
RJ-45 Pin #2 (PTT) → 3.5mm TRRS ring2 (RIG_PTT)
RJ-45 Pin #3 (MIC) → 3.5mm TRRS ring1 (RIG_AFIN)
RJ-45 Pin #4 (MIC GND) → 3.5mm TRRS sleeve (GND)
3.5mm TS tip (EXT. SPK+) → 3.5mm TRRS tip (RIG_AFOUT)
3.5mm TS sleeve (EXT. SPK-) → NC
Make sure to leave sleeve on ext. speaker unconnected:
The front of the radio features a data connection. Likely serial so this can potentially be interfaced with Digirig’s serial port. From the looks of the compatible PC50 cable I would guess logic levels, but that needs to be confirmed.