The item is not "freestanding" as stated in the title. The installation manual says that it has to be attached to the wall with the provided screws. Without attaching it to the wall the cabinet is wobbling.
Also, the design of the storage cabinet is not adequate to the purpose — it is not possible to install it "over the toilet" without a custom modification. I had to use extra brackets to set the lower back plank, and attach additional angle brackets to reinforce the lower part of the cabinet.