Unlimited Office 2021 but outlook cannot sycronize

Please note that this is Traditional Chinese Q&A Forum, any threads should be posted in Traditional Chinese. However, I will still provide an answer on English based on your initial response.  

Hi Anthony Lien, 

I can understand why this feels confusing, especially after you already purchased Office 2021 and are now seeing prompts related to Microsoft 365. 

To help narrow this down, could you please confirm a few details for me? 

• Is the issue happening on Windows only, Mac only, or both devices? 
• When Outlook asks you to purchase Microsoft 365, what is the exact message shown on screen? A screenshot would help if available. 
• Is the Gmail account a personal Gmail account or a Google Workspace / company-managed account? 
• Was the Gmail account added through the normal Google sign-in window inside Outlook, or was it set up manually with IMAP/server settings? 
• On the Mac, is Office shown as activated with your Office Home & Business 2021 license?  

In the meantime, please try the steps below: 

1. Check that Office / Outlook is activated with the purchased license 

• On the affected device, please open any Office app and confirm it shows as activated with the Office 2021 license tied to the Microsoft account used for redemption.  

2. Update Outlook fully 

• Please make sure Outlook is fully updated to the latest available build on the device.  

3. Remove the Gmail account from Outlook and add it again using the built-in Google sign-in flow 

• For Outlook for Mac, add Gmail through Outlook > Settings > Accounts > Add an account, then complete the Google sign-in and approve the permissions prompt.  
• If the account was originally added another way, re-adding it through this flow helps confirm Outlook is using the supported sign-in method.  

While my initial response may not fully resolve the issue, I truly appreciate your cooperation as we work together toward identifying the most effective solution. Thank you so much for your understanding. 

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