One of the necessary dA 5Star's features is to launch at login. While users can add it to login items in System Preferences, automatic launch-at-login with opt-out would be much more convenient and discoverable.
To do that with a macOS App Store app, Tim Schröder wrote a great tutorial on this topic.
The idea is to use
SMLoginItemSetEnabled with a bundled helper app. The helper app can be launched at login, the helper can in turn launch your main app.
So I followed the instructions. But I just couldn't get it to work. After a few hours I gave in: I downloaded the example Xcode project. It works! So there must be something wrong with my setup.
After a few more hours of comparing the differences between the sample app and my app, I finally discovered what the issue is. At this point you already guessed from this post's title. Yes that's because I named my helper
dA 5Star Helper, and it contains spaces. I renamed to simply
Launcher and it solved the mystery.