Using OAuth Authentication
OAuth requires the authenticating user to interact with Trello using the browser. The add-in facilitates this in various ways as described below.
Custom Credentials
You will need to use the app that is created for your account to obtain the OAuthClientId and OAuthClientSecret. You can find these values by visiting https://trello.com/app-key and navigating to the bottom. You must be logged in before you can view your application keys. After logging in and visiting the page you have to add http://localhost:33333 to the allowed origins.
Desktop Applications
You need to use your account's OAuth app.