To add; 

There is no Autodesk folder in the Documents directory. Usually, there is an Autosave folder within the Autodesk folder that resides in the Documents folder. On some systems, though, these folders do not get created, so the program writes the backup and autosave files into the Documents directory.

Suggested solution: 
Create and Autodesk folder in the Documents directory, and create a folder inside of it called Autosave. 

Resource to look over; 

AutoCAD for Mac writes backup and autosave files to the Documents folder. 

Sarah Emmsley
Technical Support Specialist