I think it should be “authentication” and “permissions.”

There’s pretty much no word in the English language to describe login/account creation/etc than “authentication.” The word “login” is a poor substitute. There are no good synonyms for “authentication” that encompass all its applications in computer systems.

Meanwhile, there are already lots of synonyms used for “permissions.” Given the abundance of these, and the lack of synonyms for “authentication,” choosing “authorization” to describe permissions is, frankly, an asinine decision. It adds unnecessary cognitive overhead for everyone.

(That’s not to say there’s no place for, say, Unauthorized responses, etc. Just that we should be calling the topic “permissions” or really anything other than “authorization.”)