Issue in MS Edge

Question

We have an application that users open in a browser and within the app, open Office documents. Users use I.E. to do this. With I.E. going away, users need to use a different browser. The documents don't open in Edge, an error message appears..."Office has blocked this content because your organization does not allow the sign-in method it uses". If a user opens a document from the application using I.E., it will then open in Edge, for about 5 minutes before reverting back to the error message. We've tried modifying forms-based login, opening Edge in I.E. mode, etc., no luck. The behavior where it opens in Edge after opening it in I.E., is very specific, hoping someone might understand what that means.