Now my questions. There is no bug_bot_music.cpp file. Matter of fact, the original sketch was copied and pasted out of a pdf file, so I don't have a .cpp with this sketch, as far as I know. Am I wrong to assume that a sketch doesn't have to have a .cpp file to compile correctly. And secondly, the pitches.h file is presently located in the library/tone directory, but evidently this new sketch is not finding it. So.....what am I doing wrong and where should I locate my files so the compiler finds them correctly.
What is the name of your sketch file, including extension?
Then, pitches.h (and pitches.c or pitches.cpp, if existing), need to be in the 'libraries/tone' directory, 'not library/tone' (see the plural?), inside your sketchbook dir.
And, you need to restart the IDE after you have placed a new lib into the libraries directory.