How do I anchor an acrylic claw foot tub?
I believe you just set it on the floor and let the weight of the tub and connected drain pipes keep it from moving.

If you are really worried about it moving you could mount some sort of small block to the floor behind where each leg will sit.  It would not be attached to the blocks but with for of them the tub would not be able to move.  But that may not work well with your tile floor.