WillAdams
(William Adams (Carbide 3D))
4
As noted, the .stp files should work with MeshCAM, though you may need to use some software to convert them to .stl format.
Some useful tutorials:
https://wiki.shapeoko.com/index.php/Child_Name_or_Letter_Board
https://wiki.shapeoko.com/index.php/Carbide_Create_Basics#Toolpaths_and_Geometry_Selections