Well, I do not know what they have there. Mine is, umm, exclusive. You pretty much need to be a strength athlete to use it. Yes, I am spoiled. So what.
You should not really be feeling it that much in the lower back. Make sure you are arched, keep the elbows in and as low as possible.
When doing db rows, I put both feet on the floor for stability, one hand on the bar in the power rack (a bench would work), and try very hard to keep my back parallel to the deck. To help this, I turn my head so I am looking at the shoulder that is immobile. This helps to keep me from rotating, along with the better base of support I have with both feet firmly planted.