Paypal Standard _can_ be used in conjunction with digital delivery, but it requires some some manipulation in order to make it work in a way that the purchaser can only download once the transaction is processed.
using paypal standard, you will need to configure an IPN page to store the order information once paypal has processed the transaction and sent a success IPN post.
I recommend using Paypal Pro or PayPal express, as these systems process the transaction in real time and don't require IPN. your assumption that paypal express does not allow the user to pay without a paypal account is not correct. using express checkout, the customer can checkout through paypal and use their credit card without needing a paypal account.
