If the admin has configured the Salesforce workflow to send a notification when an opportunity record is created, the notification should automatically go if the opportunity is created from CTA too. Does this not happen?
Also, is this required only for opportunities or for other linked objects too?
I have seen issues with this as well. Ours is more so in the instance of Tasks. If we sync a task back to Salesforce to notify another team of an action they need to take, they do not get an email notification.
Nitisha - This would only be required for the Opportunity.
To answer your first question, in this case the customer does not have SFDC configured to automatically send a notification. They like to selectively send notifications and thus are requesting the ability to do so from within Gainsight (maybe via a checkbox).