Connect m64 modem to ROV

Hi BlueRobotics! I have build rov and tested it with qgc. For now I want to try acoustick modems to transfer informational data. Most problem is as I don’t know how to connect it to my rov. I have just 4 wires came out of it. How connect it to pi, or pixhawk I don’t know. Can you show me some manual where I can find how to connect it.