Currently trying to bake a normal map on a dragon I modeled. I followed the tutorial as best I could(the tutorial is this one: https://youtu.be/Qp72OUGdLGQ?si=lAY77jooMIflxR_o ), but it still gave me a error message saying "Invalid cage object, the cage mesh must have the same number of faces as the active object."

I can't post the blend file in Blend Exchange because it's too big. If there's any alternate ways of sharing it, that would be much appreciated, because I can't figure out how to describe what happens, and I have a feeling this could probably only be fixed with some experimentation.
EDIT: After a little bit of research, the problem may have something to do with a subsurface modifier being on, but I don't know if I should apply it and that'll fix the problem, or if there's something else.
EDIT AGAIN: It's not the subsurface modifier. I applied that and it's still not working.