Best Litter For Nature's Miracle Automatic Box?

I just got a new Nature's miracle automatic box. What do you guys think is the best litter to use for it? I know clumping, but there's so many options out there.

I just looked it up on their website, and it's being discontinued with a bunch of 1 star reviews and doesn't seem like there is a specific mention of what kind of litter. You think they'd be trying to sell you one of their varieties of litter that is on their website, but it doesn't seem to be there.
It does say there is a one year warranty.

If it's automatic, how could it be a nature's miracle?