fernando de aratanha

I've purchased Affinity Photo at the Apple's App Store. I have the receipt. I had to format my HD and re-install all my apps. Cannot find my Affinity dmg installer on my download folder. Can I download again from Serif's site or from the App Store? Having problems signing in my account on the Serif's site. It says my email doesn't exists. Won't let me create a new account either. Please tell me what I can do. Thanks!