They just don't seem able to get it right, do they?
New Outlook client for iOS? Check.
Allow you to sign in with your Office 365 account? Check.
Allow you to use said Office 365 account OneDrive for Business? Check. Oh wait, no, you can use OneDrive for, err, non-Business. If you want to use OneDrive, you'll have to sign in for the other OneDrive service - the one you don't pay for and that doesn't have any of the files from your OneDrive for Business account and isn't associated with the email account you just added.
Why do they make it such hard work? How does this stuff get past QA? Or even past the PostIt Note stage?
"Coming soon" doesn't really cut it. OneDrive for Business has been "Coming soon" for the Mac for about two years now.
Update: A colleague let me know after posting this that a beta of the Mac OneDrive for Business client has just been released. Woohoo! Downloading now!
Update 2: For another example of how not to do it, here's a screenshot from the latest version of the OneDrive app for iOS, having just signed in to the OneDrive for Business account:
No, Microsoft, I don't want to use another account.
Guys, please get your teams talking to one another.