The Makefile issue is presumably the stopper. My best guess: The caravel/ subdirectory is supposed to be linked to the caravel project (there was some discussion about whether this should be a git submodule, or a symbolic link, or cloned directly into the project, and I'm not sure which it is right now). If not, then it is an empty directory. If there is no "Makefile", that suggests that the caravel/ project didn't get linked to the user project, which in turn suggests that some step like "make caravel" (don't know what it is; that's just a guess) was missed or is missing in the build documentation.