In regards to this, I’ve fiddled around with it a bit and it seems to work fine, at least in Sandbox Mode, contrary to what I’ve been told before, and contrary to what I was told in this thread. It did take a long time going across websites to find some help with the docs, as I’m not as tech-savvy as some.
The only difference I’ve come across compared to other authentications, is the same which is stated here:
When he says “convince” he means a Screencast, showing the ins-and-outs of what you intend to do. I sent in a 3 minute screencast showing the admin panel’s Instagram feature, the logging in, logging out, and the keys I generated in the Developer API for Instagram.
I have confirmed that although OAuth2 is the recognized standard, it is not required for this to work. I have an account, working, that has signed up, and logged in, with Instagram’s authentication as-is on Discourse, no OAuth2 or Plugin necessary.
That being said, no more than ten individuals can sign up, before Sandbox Mode locks itself. Once it is approved, it will leave Sandbox Mode, and go to “Live”.
Here is a pic of the page, showing status, on Instagram:
Why it is so difficult, I have no idea; as the OP’s thread states, it should be in line with FB’s, given FB owns IG, but I guess not. Screencast is required.