Yes, go ahead and glue your pipe to the drain's pvc black male adapter on your sump.
I spoke with Trigger directly several weeks ago and this is what they advise to do. You should be able to reach into the main drainage chamber and grasp the bottom black tube; there is a female adapter that is merely screwed into the upper male adapter (where you'll glue your pipe).
My sump was purchased same time as the tank but arrived first. I'm still working on getting saltwater into mine too.
I have to say, the build quality from Trigger Systems is really impressive.
I think the green on green was a great choice!
I went with orange pipe over my blue acrylic (Broncos fan but I live in New England, so have to support any way I can)