The ATtiny2313 processor does not have an analog-to-digital converter so...
• The A* constants are not defined (which explains the first set of errors)
• PORTC does not exist (which explains the second error)
The good news is that your development environment appears to be fine. The bad news is that the code in DVD_CNC_Stepper_Controller.cpp does not appear to usable on an ATtiny2313 processor.