I installed the Unity asset and after I enter the API key it hangs with the loading trello boards. in the bottom of Unity I see the text "TisException The authentication or decryption has failed."

Unity version is 2017.4.2f2

Thanks for bringing this to my attention! I believe this was caused by a recent change to the Trello API SSL protocol. This issue should be fixed in version 1.1.3, which is live now on Itch, and is awaiting review for the Asset Store. I'll follow up here when it's live on UAS.

Easy Feedback 1.1.3 is now live on the Asset Store as well!