Marketpress not sending confirmation email with digital download link after purchase

I'm using Marketpress with Wordpress Multisite and the Simplemarket theme. I am selling both physical and downloadable products (pdf files). I can go through the checkout process just fine - payment is processed and everything (I'm using paypal express), but there is no link on the confirmation page for the downloadable products, nor do I receive an email with the downloadable products (I receive no email at all, just the receipt from Paypal. Nothing from MP). Unfortunately, I can not post the link to my website 'cause I am using my local server and MAMP to build my site. Any insights as to what might be causing the problem are greatly appreciated.