some species will eat other kinds of snails. i would think those two would be okay together but i'm not an expert so i'd wait till someone with more experience answers.
You want to have them pick an active snail with a shell without pitting or cracks. Don't let them yank it off teh glass either, that can collapse their mantle. I know some people keep adult apple snails with goldfish. Trapdoors are another option for a goldfish tank.
My apples and goldfish get along very well.
Just be sure you pick a snail that is larger than your goldfish's mouth. Goldfish are curious creatures and they will try to eat anything and everything at least once.