Great app, cross between "Everything drawer" (Devonthink) and note taking (Evernote). Cheap compared to both, well designed. I especially like
1. the tag-based filtering options,
2. that it uses the (macOS) file system (you can browse all lists in the Finder, tags are written to the files), and
3. that i can selectively sync (download) files and folders on iOS.
Also: Very fast response to my support questions.
I don't want to sound harsh but I've tried this for a while, both the iOS and macOS app. They are fine, but not great. You'll face strange bugs every know and then, and the app starts to behave unstable as soon as you push it. I would not recommend it. A solid alternative would be DEVONthink.