Ok, well the metadata definitely won’t work if it says that, so make sure you do whatever you need to avoid that - i.e. put the key into the django admin directly. Once you get it working, you can later generate new keys and move them into lms.auth.json properly.
I would definitely change it to the domain name of the server (leave out the protocol) and leave it at that.
Anyhow, I think I found your issue: a change made two years ago and never documented requires that the slug value be set to default (which it is by default, but it seems that you have changed it here to “muni”). I suspect if you change that back to default it will solve the problem. If that solves your issue, please mark this as the solution and then I’ll try to get the docs updated.