When trying to make changes to Azure AD with Powershell, why are my credentials not recognized?

I'm trying to connect to Azure AD with powershell so that I may set some user accounts to not expire. I'm referencing this article:
https://azure.microsoft.com/en-us/documentation/articles/active-directory-passwords-set-expiration-policy/#_set-a-password-to-never-expire

I've followed these install instructions for Azure Powershell and the Azure AD Module: 

https://azure.microsoft.com/en-us/documentation/articles/powershell-install-configure/
and
https://msdn.microsoft.com/en-us/library/jj151815.aspx#bkmk_installmodule

I've attempted login with the connect-msolservice cmdlet. I am prompted for my credentials, and I provide the same ones that I use to login to the Azure web portal. My account is a global admin of the Azure AD domain in question, and I have copied my username and password precisely from my password manager. I have also disabled two-factor authentication for that account.

This is the error that I get:

PS C:\Windows\system32> connect-msolservice
connect-msolservice : The user name or password is incorrect. Verify your user name, and then type your password again.
At line:1 char:1
+ connect-msolservice
+ ~~~~~~~~~~~~~~~~~~~
    + CategoryInfo          : OperationStopped: (:) [Connect-MsolService], MicrosoftOnlineException
    + FullyQualifiedErrorId : 0x80048821,Microsoft.Online.Administration.Automation.ConnectMsolService

Please advise. I have double-checked and triple-checked my credentials.