You will need to have "Unknown Sources" checked in your settings, and getting to that part of the Settings app is somewhat device specific. After that, you'll be free and clear to install the app. We are always making improvements ahead of the official release of 1.0. Those of you who decide to test the app will see that there is definitely some work to be done, but we're getting there. And the version that we are releasing to the public today is 0.4. Between 0.3 and 0.4 some visual clues were added to navigate the app, as well as a few tweaks to the images used in the app. If you want to leave some feedback, you can do so by leaving a comment on this post, and as for future updates, which will come regularly, you will be able to find those on the forthcoming "Companion App" page under GTAV in the NavBar.