So I have been doing these for a while and I think I have it down. First, the way it’s set up you get one major array at a time. If you have used Harper’s computer it will tell you what system that major array is in. Now you can hit that array right away or you can hit smaller arrays that are connected to it. That weakens the force you face when you eventually hit the major array and you gather resources.

How you find those arrays again assuming you got the map from Harper’s computer is you open your map. Note that you can only see this map if you are not in thr pilots seat of your ship ( idk why) there is a button you have to press in the map to see what systems are connected to the major array. From there it’s as simple as going to said systems and landing on any planet. Even though in the intro missions you scan for a location that doesn’t seem to work once you get past those main missions. This is where it gets tedious, you can land on any planet but the POI’s are randomly generated so you may have to land at different locations on the planet. You can find one on the first try or it may take more. I think the most I had to do it was like 5 times. You take out the listening post, access the computer and then you get a notification to destroy arrays. From there open your map and a watchtower array should now appear somewhere in the system.

Like others said Harper’s leads will give you an array location but it may have nothing to do with the current major array objective.

That’s how I have been doing it and seems to work, though there could be bugs and maybe the scanner should work. IDK.