Put it on your home screen.
Installed, it opens in its own window with no address bar and no tabs around it - and it is one press from a home screen or a dock rather than a search through open tabs. On a phone at 3am that is one fewer thing in the way.
There is no app store listing and nothing to download. Your browser does it, which is why it works the same on a phone, a tablet and a desktop, and why nothing about it lands in a purchase history.
This browser has no install of its own. Open usemaybe.app in Safari or Chrome and the option appears - or pick the device you want to set up below.
Setting up a different device?
Installing changes nothing about how your conversations are held. They are still sealed on the device before they are sent, and we still cannot read them.