Solar panels & controller - am I missing anything?

Exactly which controller have you bought? The link shows 3 different models: 5, 10 and 15A. As noted, you need at least 15A. Buying unknown brands is taking chances, though this one has some record already - known for low prices. I suspect they are pirating all their models. I would get some simple 15-16A model from known brand like ASC, but that one would will cost $50-60.

Yes, cables of proper gauge and length (no too thin or too long), terminated with lugs, and a fuse between controller and battery.