KLT Profit installs straight from your browser: no app store, nothing to download. About 30 seconds, and it opens full-screen like any other app.
Open klt-profit.pages.dev in Safari (it has to be Safari for this part).
Tap the Share button at the bottom of the screen, the square with the arrow pointing up.
Scroll down the list and tap Add to Home Screen , then tap Add.
Open klt-profit.pages.dev in Chrome.
Tap the three dots in the top right corner.
Tap Add to Home screen (some phones say Install app), then confirm.