Yes, the Apple App Store version was flawed but I found it on Microsoft's website. I downloaded the app from Apple App Store recently like others here, then deleted it after it kept asking for a subscription. That was confusing, so I spent some time going through blogs, and found a link to download the app from Microsoft's site. It works although it seems to be missing some features like creating a new email from a template.
Often bloggers will repeat what they have read elsewhere and not try the solution themselves. In this case, the app on Apple App Store has the limitation (for now) of needing a 365 subscription. I have the install file from Microsoft but couldn't easily find it again. I found the link in one of the blogs announcing the free version.
Good luck, don't give up!