First attempt at B2 cloud storage backend fails. What to put where?

I’m getting “Failed to connect: 401 - bad_auth_token:” when trying to set up my first B2 cloud storage backup.

Apparently, I do not understand what to put where when using Backblaze. I need to know what B2 data to fill in for ‘B2 Account ID’ and ‘B2 Application Key’ in Duplicati. And the documentation doesn’t help me enough. The account id is an email address (but not in B2’s examples, where it is an ID which I have no idea where to find)

Backblaze which number is which might help, although manual’s B2 Cloud Storage could use an update… This is a somewhat new added feature of B2, so various things are still catching up with change, I suspect.
Application Keys is Backblaze’s attempt to explain it. Basically, there are now two flavors for an ID+key pair. Using either kind should work, but the new application key (and associated keyId) is better security practice.
Locating the Master Application Key and Master Application Key ID Pair may also help with how to get them.