There is a Guide inside the app that explains how it works. Although, from your comment, it sounds like your problems might jave been with Google Play and not with the app itself.
最新動向
• Fix some files not being selectable in the file picker on some websites. • Colorize the logcat and add a search option. • Allow selecting a bookmark favorite icon from the filesystem. • Fix a number of small issues and bugs. • Bump the minimum API to 26 (Android 8.0).