iOS installation
Step 1
Install the TestFlight application on your phone from App Store. This is a prerequisite for apps that have not yet been publicly published on the App Store.
Step 2
Open your TestFlight app on your phone and you should see the KnowU application there. Install it.

You are done! You can now find KnowU app in your phone like a regular app.

Updates
When new versions are released you will be able to update the app via TestFlight, the same way you installed it.