When installing the Office Addons, I get the error message "This application has been blocked by the administrator as it potentially ...

If you receive the following error message: "This application has been blocked by the administrator because it potentially poses a security risk to your computer", then your Windows settings are not the recommended standard and should therefore be reset. Microsoft has an appropriate guide at https://docs.microsoft.com/en-us/visualstudio/deployment/how-to-configure-the-clickonce-trust-prompt-behavior?view=vs-2015. Follow the steps in "Activating the ClickOnce Trust Request." The string value for MyComputer must be Enabled.