Yes it has to be the right one, you should be able to order one from any good auto parts store. Do not worry about what type of clutch or flywheel you have, the important factor is the type of gearbox, as the bearing is a press fit onto the bearing carrier. Just walk into Repco or Supercheap and tell them you want a throwout/thrust bearing for a (whatever model you have) Corolla with a 5 speed and they will look it up in their catalogue.
But seriously, I think you would know if you forgot to put the throwout bearing in.