How to connect NASA AIS engine to Garmin Plotter

[emandvee44]

Apologies if this has been covered before but my search facility is not working.
Can anyone advise how to connect a Nasa AIS engine 3 to a Garmin plotter GPS Map 551?
The instructions with the AIS unit are not clear, at least to a non techie like me.

View attachment 42779

 

[David2452]

Pin #2 of the D plug to NMEA0183 + in of the Garmin and pin # 5 of the D plug goes to the NMEA0183 - in of the Garmin.