Hi,
Yes, this is possible. Your order confirmation email is a PHP template, and inside it you have the full list of the products that were purchased, so you can show an extra block (your login / hidden menu link) only when the order contains the digital item, and hide it for orders that are physical only.
In your HikaShop backend go to System > Emails and open the email your customers receive: the "Order creation notification", and/or the "Order status notification" if you would rather reveal the access only once the order is confirmed and paid. Whatever you save there is kept as an update safe override, so a HikaShop update will not overwrite it.
At the spot in the body where you want the link to appear, add this block and set your digital product id(s):
<?php
$digitalProductIds = array(12, 34); // put your digital product id(s) here
$hasDigital = false;
foreach($data->cart->products as $item) {
if(in_array($item->product_id, $digitalProductIds)) {
$hasDigital = true;
break;
}
}
if($hasDigital) {
echo '<p><a href="'.HIKASHOP_LIVE.'index.php?Itemid=123">Access your content here</a></p>';
}
?>
Replace 12, 34 with the id(s) of your digital product(s) (you see them in the ID column of the Products listing), and Itemid=123 with the id of your hidden menu item. Customers who bought only physical products will not see the block; anyone who bought the digital item, alone or together with physical products, will get the link.
If you have many digital products and would rather not maintain a list of ids, you can rearrange the code to use a custom product field, or something else based on how you characterize digital products in your shop.