I recently ran across an issue where I had downloaded Microsoft Office 2019 fresh from the internet, installed the software, then attempted to open Microsoft Word. Upon opening it asked me to activate/sign in. I signed in with the client’s email and password successfully however the next page was supposed to show what licenses were available but instead simply showed a blank page similar to the image below.

I attempted many things to try and resolve the issue, however the simple fix was to Right Click inside the window, or hold the Control key down on the keyboard and click inside the window with your mouse cursor. Once clicking it offered a “Reload Page” option. If the page activates properly from there, you’re all set! Otherwise select the “Reload Page” option and it will refresh the blank page and should activate.