This pop-up did not appear until the most recent Office 365 for Mac update. Now it appears every time I open an Office application, probably because I refuse to choose either data sharing option.
The options in the pop-up - full diagnostic data or basic diagnostic data - are the same options in the Word Preferences window. But the Word Preferences window seems to let you choose whether or not you will share personal data at all (I won't). There is
no such choice in this new pop-up, so it keeps reappearing - apparently forever.
I do not know if this is an error on Microsoft's part or if they are becoming more insistent on getting data from users. As a work-around, I am tempted to just start each Office app in the morning, deal with the pop-up once, and leave the app open all day
while I open and close files. Hardly desirable.