Free motion quilting is usually done by dropping the feed dogs, so the foot doesn't really matter. I have used a regular wide zigzag foot, just because it allows me to see better than a narrow foot. No foot is required to FMQ, you guide the fabric under the needle, foot only helps keep the fabric feeding without wrinkles ahead of it. You can also leave the foot off completely (make sure to drop the foot control) but must be extremely careful of fingers!

The darning foot should work for free motion quilting; just remember to drop your feed dogs.

In the absence of a walking foot, I might recommend the standard presser foot that came with the machine. In doing so, I would dial back (reduce) the pressure of the foot so it doesn't push the top layer of the quilt so much.