Since the dev turnover I believe the backends for the public examples were under individual account and no longer available.
Have you tried the tours?
For auth examples, I wrote a somewhat thorough example in the dgraph blog titled, “Putting it all together”
Dgraph does good right now for your simple apps but when you need analytics or rock solid security it will fail in its current state. Hopefully development will get back on track to fix these vulnerabilities and mature the query languages.
Keep an eye out from the CTO @gajanan who should be posting a roadmap soonish.