Salesforce/Box Integration Issue: unauthorized_client, This app is not authorized by the enterprise admin

[santoshprolocity]

Inspite of accurately following the instructions provided in the https://github.com/kylefernandadams/box-for-salesforce-blueprints we are still encountering the issue when we Setup Box Platform Settings, after uploading the sfdc_box_config.json

{"error":"unauthorized_client","error_description":"This app is not authorized by the enterprise admin"}

Kindly advise what we are missing. Just FYI the same setup between Salesforce Sandbox and Box Sandbox environment worked fine