Here’s the connections of interest and pinouts:
Based on this, the audio cable is:
DIN5 pin 1 (DATA IN) → 3.5mm TRRS ring 1 (RIG_AFIN)
DIN5 pin 2 (GND) → 3.5mm TRRS sleeve (GND)
DIN5 pin 3 (PTT) → 3.5mm TRRS ring 2 (PTT)
DIN5 pin 4 (DATA OUT) → 3.5mm TRRS tip (RIG_AFOUT)
CAT cable:
DIN6 pin 1 (GND) → 3.5mm TRRS sleeve (GND)
DIN6 pin 2 (SERIAL OUT) → 3.5mm TRRS ring 1 (RIG_TXD)
DIN6 pin 3 (SERIAL IN) → 3.5mm TRRS tip (RIG_RXD)
The serial port is 5V logic levels which would work with Digirig’s logic levels configuration. It’s 3.3V but compatible/tolerant of 5V.