Activate in the app (Earn More tab, More challenges).
Shop at James Squire, Eveready, Little Creatures, Durex, L'Oreal Paris at Chemist Warehouse, Blackmores at Chemist Warehouse, Skin Doctors, Elizabeth Arden at Chemist Warehouse, RIDER Zero Carb Lager, Winter Brews.
OK, that store list is weird. But if you click through the challenge it goes to a page in the app that has links and cashback rates to the particular stores.
Edit: it appears to be a new boosted brand promo, maybe there's a good deal in there? I have no idea. I saw Chemist Warehouse and thought it was just CW.