Here are some pics of how I did ours.
Here is a list of supplies, as best I remember.
female thread to solvent connection PVC union
solvent connection to female thread PVC union
male thread to sump connection (gray plastic) (was in bag with sump pump hose)
Sump pump hose (came in 25' length)
90° sump pump connector (gray plastic)
Two hose clamps
The gray sump pump 90° elbow goes into the container opening.
You'll want to spin the union onto the threads on your camper and tighten it down, then glue the PVC 90 on to it. Hand tight is all you need when attaching the union onto the camper threads. Doing it this way you'll know the 90° elbow will be pointing down when you go to use your drain assembly.
Hope that helps!