Just a naming error (I think). Steambu.h should be streambuf.h

Not a naming error, but a 'not-reading-the-installation-docs' error.
You unzipped gpp281b.zip with a non-LFN unzipper. The actual filename
inside the .zip *is* streambuf.h, and using an LFN-aware unzipper on
a LFN-aware platform would have given you a file called streambuf.h, 
indeed.