AEM AaCS - collections - link sharing error

Hi there, users are trying to share collection using the "Link sharing" option in UI, adds a user to share with, subject etc and clicks share, error prompt displays with the following info:

"Share Link : an error occurred in link sharing"

Is there something that needs to be configured for this feature to work? cant find anything except that for AEM 6.4 the email server had to be configured