Here's a tip that I thought might assist some people. I'm trying to interact with DropBox and OneDrive and for the purposes of the workflow, needed to use the workflow Initiator as the authorizing user.
Here's the trick: don't forget to change the format of that value to email address by clicking on the orange Fx button to the right. It defaults to login name and that won't work.
This document was generated from the following discussion: Office 365 integration actions: Return type