The :closed error is probably due to a TLS incompatibility between Erlang (18.3.2 and later) and Microsoft servers with modern (SHA256) certificates. The issue has come up in various places over the last year or so, and I just happened to blog about it earlier today: https://blog.voltone.net/post/9 (last section).
TL;DR: you will have to force the connection to use TLS v1.2. The way to do this depends a bit on the TLS/HTTPS client you’re using and the way it wraps Erlang’s :ssl options, but if you’re using the OAuth2 library, this post should help.
