@darrene Funny, but I had to change the config to remove the square brackets and replace them with curly brackets around the config parameters to get the config.js file to be accepted:

{ module: 'MMM-fitbit', position: 'top_center', **config: {** credentials: { client_id: <client_id>, client_secret: <client_secret>, }, resources: [ 'steps', 'floors', 'caloriesOut', 'distance', 'activeMinutes', 'sleep', 'heart' ], update_interval: 60 **}** },