yea ofxSyphon seems to be all over the internet in various forms…
If I clone and install astellato’s github version (it has the newest code) and follow his installation instructions, the example works for me (I moved it to OF/examples/addons).
OF is annoying in its hierarchy of folders, and its habit of occasionally changing them between releases which breaks all sorts of things. Make sure the example project can find the ofxSyphon addon.