Open Word on the Web and log into your Microsoft account.
Open a new or existing document.
In the Insert menu click on the Add-ins button and go to the Store tab.
Look for Wordtune in the search bar and click the Add button.
You can now launch the Add-in using the Wordtune button in your Home menu.
Note: If you are using the Simplified Ribbon layout, you will have to click the ellipsis (...) in your Home menu to access the Wordtune button.