Depending on your Lowrance unit, and your installation, it might already be running a NMEA2000 GPS. If this is the case it is best practice to have only the data wires joining the Raymarine Seatalk NG network (or to remove the power source from either the Lowrance or Raymarine network), otherwise you'll have 2 power sources on the same network. You'll also need to have only one resistor on each network.
If you don't have an existing NMEA2000 network, you'll just need a straight cable from the Lowrance and a straight cable from the Seatalk NG network, cut and solder, ooorrr just use the adapter cable.
Haha it makes sense in my head anyway! If it sounds too complicated, get the marine electronics company who you're getting the autopilot through to do it for you. I can recommend depending on where you are located.
0800 BAY MARINE www.baymarineelectronics.co.nz