I have downloaded a few models on GrabCAD but when I load the assembly on Inventor it asks me to identify the file for all the individual components. Any ideas?
I guess that you have only the assembly without the parts and subassemblies (1) or they are not on the correct place in the directory structure (2).
assuming that you are opening Inventor files with Inventor
at (1): you can only open the assembly and skip the parts in the appearing dialog resulting in an model that you can't modify
at (2): you can either move the parts into the correct directory structure or act in the same dialog as (1) but you can allocate the new file position in the directory structure