The hub works straight from a browser. Installing it only gives it its own icon and window on your phone or computer, like any other app. There is nothing to download from an app store.
iPhone / iPad Safari
Open this hub's link in Safari
Tap the Share icon (square with an arrow, at the bottom of the screen)
Scroll down and tap Add to Home Screen
Tap Add. The hub now has its own icon on your Home Screen
Android Chrome
Open this hub's link in Chrome
Tap the ⋮ menu (top right)
Tap Add to Home screen or Install app (wording varies by Android version)
Confirm. The hub now has its own icon
Windows / Linux / ChromeOS Chrome or Edge
Open this hub's link
Click the install icon in the address bar (a small monitor-with-arrow icon), or open the ⋮ menu and choose Install…
Click Install. The hub opens in its own window and gets a shortcut in your Start menu or app launcher
Mac Safari or Chrome
Open this hub's link
Safari: File menu → Add to Dock…
Chrome: click the install icon in the address bar, or ⋮ menu → Cast, save, and share → Install page as app…