This app is a “progressive web app (pwa)”. It is designed to work on all platforms including desktops, tablets and phones. It is the latest, greatest way to design websites. In the past an app had to be designed twice: once for android and once for iphones. Both native apps had to be submitted to app stores. (costly) Updating apps were difficult. PWA’s are basically a website that has added coding to work as an app. And should be faster than traditional apps and will (somewhat) work without internet access.
To install this app, a pop up window should have popped up to ask you if you wanted to “add to homescreen”. If it did not, you can add it manually.