The Unifit comes with four small screws, that work fine on wood or vinyl floors.Don't ever listen to anyone at Home Depot.
If you have tile or concrete, then you drill 1/4" holes for the green inserts.
The screws will thread into those.
If you ever have to replace the wax seal, you will need to be able to remove the adapter.
An adapter installed on tile using the green inserts and the screws that come in the Unifit Box.