Windows 10 doesn't recognize a Microsoft account

Question

I'm setting up a computer and the main user is going to log in using Microsoft credentials (it's an Office 365 account). I reinstalled the computer, created a local user named "admin", and now, from that account, I'm trying to add another account by going to Settings -> Family & other people -> Add someone else to this PC, where I enter the Office 365 email address as the email address of new user, only to be greeted by this:

It looks like this isn't a Microsoft account. Try another email address or sign up for a new one.

It definitely is an Office 365 account that was being used to log in in the previous computer. Earlier today, that same email address was used to log into that same machine, but with no local admin account present at that point.

Any ideas what's going on here?

Solution

Ok. I believe I've got the bottom of it. These computers were set up for organization and the one I re-installed I set it up for personal use. During the installation process you get to select that:

Once the computer is set up for an organization and you log in with an Office 365 user account, then the computer seems to be tied to the Office 365 account. The computer is not part of an Azure AD domain and the accounts are not Microsoft accounts, yet, they can log in straight into the computer.

Comments

[harrymc]

A Office 365 account is used for activating Office, not to logon to Windows.

[Kurru]

Let us continue this discussion in chat.

[harrymc]

Could you please list in your post the exact steps that were done regarding user accounts, and what was done for passing from local to Microsoft account. For the question by Ramhound see this link.

[Kurru]

@harrymc: there's a chat going on as well. I expanded on the question, but I'm not sure what other details to give, this is pretty much all I've done.

[Luke Puplett]

How did you reverse your original choice?

[Kurru]

@LukePuplett: by triggering a re-install of Window. Windows 10 comes with a feature that allows you to do a factory reset losing all files.

[Joel V. Earnest-DeYoung]

Instruction to join Azure AD after Windows is already installed are at docs.microsoft.com/en-us/azure/active-directory/user-help/…