a company asked me if i had the 3D files and the mockup samples. What exactly are mockup samples? I only know that from the web design area.
Mockups are models to help you see if you got the dimensions right. Usually scale models made out of cardboard or similar material so you can fix any mistakes before you start working with the real build. If you have a prototype that you have already built, that would be even better than a mockup because it is the real thing.
mockup in cad are often sample designs of how a part looks from the outside (in this case drivers) so you can integrate it in your drawing. Outside cad they are the same, they are mostly full size expample build that does not have to work, they need to give a visual presentation of what it will look like... a bit like concept cars that are made by big companies, where they want to show design and engineering clues, but that not necesairy work already.