is your password particularly long? Say more than 11 characters?

Have you tried safe mode. Often anti virus and other security suites interfere with the setup process. This can be bypassed by using safe mode.

Restart the operating system in safe mode with Networking. This loads only the very basics needed to start your computer while enabling an Internet connection. Click on your operating system for instructions on how to start in safe mode: Windows 8, Windows 7, Windows Vista, Windows XP, OSX

I'm using Xubuntu Linux, and I don't have an AV. My password is 9 characters.

Is your firewall allowing Thundebird to check it's online database of configs?

What exactly is the error message you get? When the wizard is checking for account settings for outlook.com it should simply state found as they are in the database.

Matt said

Is your firewall allowing Thundebird to check it's online database of configs? What exactly is the error message you get? When the wizard is checking for account settings for outlook.com it should simply state found as they are in the database.

The firewall isn't a problem. The exact error message after attempting to set up the account is: Configuration could not be verified - is the username or password wrong?

Since they are the very username and password I use to access the account through my browser, the response to the question is "no." Without any further insight as to the problem, I remain at a loss as to how to make it work.

Do you have two-step verification on the account?

http://windows.microsoft.com/en-ca/windows/app-passwords-two-step-verification

sfhowes said

Do you have two-step verification on the account? http://windows.microsoft.com/en-ca/windows/app-passwords-two-step-verification

Ah, thank you. Setting an app password was apparently what I needed to do.