On the registration page, double click the Insert record server behaivor. The password column is set to:
<?php echo ((isset($_POST["UserPassword"]))?$_POST["UserPassword"]:""); ?>
change that to;
<?php echo ((isset($_POST["UserPassword"]))?md5($_POST["UserPassword"]):""); ?>
You will also have to change the login page. on the Second page of the Authenticate user server behavior, change the password binding:
<?php echo ((isset($_POST["userpassword"]))?$_POST["userpassword"]:""); ?>
to:
<?php echo ((isset($_POST["userpassword"]))?md5($_POST["userpassword"]):""); ?>