Yes, that sounds like the problem. The quick connect plugs into an adaptor that screws into a STANDARD return. If you have a light-return, it may not allow the adaptor to screw in correctly--I've only heard and seen pictures of those fittings, so I don't know if they are now standard fittings, or if they use their own eyeball fittings.

If it's not a standard fitting that the adaptor can screw into, I really don't know WHAT you can do that's easy.
Here are the options I see:
1) Replace the return light with a standard return and find another light alternative.
2) Contact Polaris and see if they have an adaptor to fit that return (I doubt it). Contact the light manufacturer and see if THEY have an adaptor to make it a standard return.
3) Replace the Polaris with a different automatic vacuum that doesn't use the return--like a Kreepy Krawler type or a robotic.
4) Get inventive: Here's my idea. Install a second return near the first, but use a standard return for it. Behind each return, put a cutoff valve and have them both lead into a Y connection. Put the Polaris adaptor in the standard return. Then, for normal use, turn off the standard return and turn on the Light return. For vacuuming, turn of the Light return and turn on the standard return, connected to the Polaris. This will take about $50 in parts, plus the correct size hole-saw, and does require lowering the water to cut in another return. Still, it's probably the cheapest alternative.

Normally, with a Polaris 65 or 165, you just turn off the pump, hook up the Polaris and all its hoses and dump it all in the pool, then turn on the pump. You don't have to prime return-side vacuums the way you have to prime skimmer-side vacuums--the return pumps the water in for you.