Symptoms
When you try to add a new Gmail account in Microsoft Outlook, you encounter the following symptoms:
  • You are prompted for authentication, and your credentials are not accepted.

    The screenshot for the symptom
  • You receive the following error message in Outlook: 
    Your IMAP server wants to alert you to the following: Please log in via your web browser:
    http://support.google.com/mail/accounts/bing/answer.py?answer=78754 (Failure)
    The screenshot for Symptom 2
Note If you are using Outlook 2016 for Mac or Outlook for Mac 2011, the prompt and error message may look different, but the method for resolving the issue is the same.
Cause
This issue occurs when you try to sync to a Gmail account after July 15, 2014 and Basic Authentication has not been enabled for your Gmail account.

Google has increased its security measures to block access to Google accounts after July 15, 2014 if those accounts are being set up or synced in apps and on devices that use Basic Authentication.
Resolution
To resolve this problem, enable Basic Authentication for your Gmail account. To do this, go to the following Google website, and then select Enable when you are prompted about whether to let less secure apps access your Gmail account:


For additional security, consider enabling Google’s two-step verification and app passwords as documented at the following web pages:

https://support.google.com/accounts/answer/180744?hl=en

https://support.google.com/accounts/answer/185833?hl=en&topic=2784804&ctx=topic


Note The workaround described here takes you to the page in the following screen shot. You click Enable to work around the issue.

The screenshot of the page

More information
For more information about the "password incorrect" error, go to the following Google website:

Third-party information disclaimer
The third-party products that this article discusses are manufactured by companies that are independent of Microsoft. Microsoft makes no warranty, implied or otherwise, about the performance or reliability of these products. 

Microsoft provides third-party contact information to help you find technical support. This contact information may change without notice. Microsoft does not guarantee the accuracy of this third-party contact information.