My understanding is a pre-meshed crack requires 3D solid elements. If there is an ANSYS verification model that shows a 2D model, I don't know about it.
If you want to proceed with a Pre-Meshed Crack, I suggest you create the crack faces in a 3D solid body using SpaceClaim, but you need good geometry creation skills.
I recommend you use a Semi-Elliptical Crack, which requires no geometry preparation.