I have installed Janus via synaptic in Ubuntu.
I can serve the demo pages using python -m http.server but that’s about as far as I can get. Requests to start any of the demo are complaining about not having a token.
Tried going to admin.html, entered the password and it says Couldn't contact the backend: is Janus down, or is the Admin/Monitor interface disabled?
How do I enable the admin?
I’d say start from learning what the demos do, by having a look at the documentation for janus.js. Once that’s clearer, you may want to have a look at the documentation for the Janus API itself, which you can use to write your own client stack or use a different one (e.g., Janode). In both cases, understanding how plugins work (especially those you plan to use) is definitely a good read.
For a general understanding of how Janus works, there’s a lot of material available, including many presentation videos.
The problem is that I still can’t access the demos.
That’s what studying the documentation is for 
Where in the documentation does it explain that? I see what the stack overflow pages are talking about when they say this:
ditched janus for a cloud service - eg Twilio - instead. IMO janus is not worth the hassle, and their dev community is detrimental to one's wellbeing. Avoid! – bionara just now Edit Delete
If you’re here just to insult us, then I’m afraid I have nothing else to say. This is an open source project, where you’re supposed to do some homework of your own too, and I most definitely don’t work for you.
Yep, stack overflow is right. You aren’t helpful in the slightest.
I asked where I could find that in the docs, (which are very poorly organized).
I only help those that want to be helped. You’re not providing any detail except “it doesn’t connect”. You’re not saying which address/port the HTTP server you spawned is bound to, what address janus.js is configured to connect to, if there’s firewalls/NATs in between, etc. Without details, how exactly am I supposed to be “helpful”, except pointing you to where you can learn more? I pointed you to the docs exactly to allow you to understand how the process of connecting to the API server works. If they’re poorly organized, well, sorry about that: that’s usually where community members that want to be helpful, or learn, step in to help, not where lazy ones whine. Feel free to return to the comfort of your SO bros.
Forget it, you are an elitist twat with your “read the docs” response.
I’ll find another WebRTC server.