You should be able to adjust the Travel Dimensions to match those of the machine, see:
Machine selection in Carbide Create has no affect on anything in current versions and is simply an artifact of earlier versions which would calculate feeds and speeds and limit stock size.
For setting zero relative to stock please see:
Have you tried doing one of the tutorials?
https://docs.carbide3d.com/tutorials/#shapeoko-tutorials
Please post a .c2d file, generated G-Code, step-by-step notes on how you are securing your stock and setting zero relative to it and managing all tool changes an a photo showing an attempt at cutting still in place on the machine and we will do our best to sort things out with you.