Hi,
in your site I see still ajax alert and request get 500 error, this happen when there are a server side error, so we need to have access to your PHP error_log to check.
after you register it doesn't send the activation link to the email address
Easy Profile extends Joomla user management, so registration/edit profile pages and process are managed by Joomla (also send mail after registration), I see the BT Social Login source code and this module replace Joomla registration (not only page but also process and send mail process). You will find the code to send this email in file /modules/mod_bt_sociallogin/helpers/helper.php after line 800.