This error means that your service user that was provided to us to connect to your CRM is not able to access your CRM. You can see the service user and update the password we have stored for the connection by going to Settings > ClickDimensions Settings, and clicking on "Service Credentials". The user you see there must be an active CRM user with Read/Write access mode and the ClickDimensions Service security role. If the password for this user has recently expired or been changed, you must enter the new password in the Service Credentials dialog.
If you are unable to access this dialog or cannot update the password, please open a support ticket so our team can guide you further.