Hi,
After the payment, PayPal will send a payment notification (IPN) to your server, which will then change the order status from "created" to "confirmed" (or the order statuses that you configured in the System>Order statuses menu and the "verified status" setting of your PayPal payment method). So first, check that your orders are getting confirmed automatically after the payment.
If not, then you have a payment notification issue:
www.hikashop.com/support/documentation/i...or.html#notification
If yes, then, you need to check the "Download" column of the System>Order statuses menu. Only the order statuses enabled in that column will make the downloads available for the customer. So if your orders get the "confirmed" status after the payment, you need to make sure that "confirmed" is enabled in that column.