Feedback requested: 118 out of my last 200 signups never link a Trello board

I make Slateboard, a little application that converts Trello cards to weekly reports for clients. Signup is easy. Onboarding is tough. Of the last 200 users who signed up, 118 didn't link their Trello boards.

I assume the OAuth screen intimidates users, since it requires permission for everything without seeing any value first. I have thought about showing a sample report with made-up data before connecting. Maybe that's wrong. That's just a delay tactic that will make users leave on another page.

If you have some time, sign up and tell me where you stopped. Honest answers are more useful than kind silences. Did you think this seemed suspicious?

And to any users who have improved a flow like this, did the sample-data page help conversions, or did it seem deceptive?