Linking Google Apps if the Trello App is already installed
Business Class accounts can connect their Trello accounts to their Google Apps domain in order to invite domain members. However, if you already have the Trello App installed in Google Apps, the linking instructions in our Business Class User Guide won't work. Instead, you'll need to manage the connection from within Google Apps.
Connecting to Trello from within Google Apps
From within Google Apps, navigate to your domain's Admin console. Click "Apps," then "Marketplace Apps," and select "Trello Business Class."
From there, expand the "Settings" section, then click "Go to Trello Business Class for setup" This should open a Trello page that will allow you to link your domain to Trello. Click your Workspace name to continue linking your domain.
This will initiate the linking process between Trello and your domain.