Not open to the public - Need an access code
Despite the App Store page indicating the app can be used by anyone, it appears you need some sort of “access code” to actually use it, and I can’t see anywhere that we are given an access code. After trying to google a solution, I can see this app is being used as part of a medical study into insomnia, and part of the analysis is based on how many issued “access codes” are actually activated, so it would appear this app is not open to the public, but only available to those who have been issued a prescription to use the app and provided with an access code.