Here are the steps that you need to follow to change your firewall settings: You can try changing your firewall settings to see if that fixes the problem. If you are using a third-party firewall application, then it might be blocking Outlook 365 from accessing the internet. You can also activate Office 365 with the product key. A copy of the Office app will be activated on your Windows 10. Now, open Outlook on your system and enter the email address to which Office 365 is subscribed.After completing the Online Repair process, the “ Office 365 is installed now” message will appear on the screen.A notification will appear: “ We’ll download files to repair your installation.” Click Repair to start the repairing process. Select Online Repair and click Repair.If you choose the Online Repair method, you might lose the Office 365 customization and settings.Finally, a notification will appear on the screen. In the confirmation window, click Repair to start the repairing process. Here we will perform both the repairing methods. At the same time, Online Repair involves reinstalling Office 365 apps to fix all the problems with Office 365 apps. The Quick Repair will fix the common issues quickly. Note: There are two ways to fix Office 365 apps – Quick Repair and Online Repair. Now you can see the User Account Control Prompt will appear on the screen.Click the Change button to repair Office 365. You will see two options – Change and Uninstall. Find the Microsoft 365 app and click on it to see the available options.Select Apps & features to display all the installed apps on your Windows 10.Go to the Start menu and click the Setting icon to open the Settings or type Settings in the search bar.However, it might not be helpful in addressing all the issues associated with Office 365 applications, but common issues like Outlook or any other app not working properly can be fixed easily.

Microsoft provides a free Office 365 troubleshooting tool that can resolve most of the common problems related to Office 365 applications.

Delete and reinstall outlook