The error on checkout means that you have not entered the correct information for connecting to your gateway.
re you using PayPal Pro for your gateway? If so, make sure that you have the correct API Details entered.
see the following for details on signing up for a PayP{al Payments pro account and obtaining API Information:
signup_paypal.php
in the Google Anylitics account, do you have data sharing set to Other Google products only? This will prevent cafe commerce from being able to connect to it.