Sorry for the confusion. This chapter didn't have a code download as the the "AcmeApp" example used in Chapter 20 was just a C# Console Application with 5 additional classes added (ClassA.cs - ClassE.cs). Each ClassA.cs type class had 10 lines in it called with just "// line A 1" through to "// line A 10", ClassB had "// line B 1" etc.
If you go to File, New, Project.. and create a new Visual C# (or Visual Basic) Console Application solution and add 5 files to it in a similar way you should be able to follow along.
If you need anything else, just let me know.