If your CBX API Key is in user or failing installation, our recommendation is that you clear your past due tasks prior to install. You might also consider an option for the Admin to turn off the Past Due Task feature for your Users.
Next, log into Chrome as the User who received the invite (if you are logged into Chrome as a different User, you cannot activate the extension with the API key):
Go to your Settings in Chrome.
Turn off Google Chrome Synching.
Request another email invitation from your Admin and follow the steps to reinstall the extension.
Turn Google Chrome Synching back on.