Help With Dimensions!

Hi. New to GrabCad and to 3D printing. I downloaded an .stl file to use in my 3D printer. I wanted to see what the exact dimensions of the model wee, so i opened the file in Fusion360. The measured dimensions make no sense. They are way larger than the size of the model. (When I import into the Creality print program, it give overall dimensions that are what it does print it as).

Why can't I dimension the model in detail in Fusion?