Issues since I switched to iOS

I had this app on android and it was great! I use it for work to scan and email receipts. Since I switched to the iPhone I have had nothing but issues with this app. I even purchased the $4.99 version. I tried installing the paid version on my iPad and it said I didnt own it, now the App Store says that I need to pay $4.99 for the app again??? I have NEVER had the email function work on my iPhone. Every time I go to email a .pdf it says I need to configure my email. I have the mail app and gmail app both configured on my phone, as well my email is configured into the app. Very disappointed that i wasted $5, for something that now I dont own and cant use the most basic functions of the program.

Macgiff about Tiny Scanner - PDF scanner to scan document, receipt & fax, v4.1