We also have the best experience with Catsan Bianco Fresh, also with regard to dust. In the beginning it was great - after a little over a year it often sticks to the floor - possibly because of the 3rd cat (a rescued foundling)
which is now grown up. Now I mix in some Catsan Ultra Plus and it's good (much better). We use the clear rubbish bags from Migros as plastic bags.

The manufacturer recommends "clay litter" like Everclean Litterfree Paws

From Whisker: The best litter for Litter-Robot is clumping clay litter. We recommend a high-quality, standard-weight, clay-based clumping litter. Some silica gel litter beads and crystals can also be used with Litter-Robot, as long as they pass through the screen. However, translucent or white-colored litter (most often seen in crystal litter) may impact the litter level and Drawer Full Indicator (DFI) accuracy in Litter-Robot 4 and are therefore not recommended. Alternative, plant-based litters typically do not work with Litter-Robot as these may not be filtered properly through the sifting system. Litters that do not work in Litter-Robot are the strictly absorbent, non-clumping or loose-clumping litters, newspaper-based litters, and absorbent wood pellet litter.

Ich nutze Catsan Bianco Fresh ist super

We have "Signal cat litter clumping". It's very fine. Available from the Coop