Tap Download the app. Chrome will warn that the file can harm your device —
that message appears for every app not installed from the Play Store.
Open the downloaded file. Android asks to allow installs from this source; allow it.
Tap Install, then Open, and sign in once.
Or install it straight from this page
No download, no security prompt. Same app, same offline working.
If the button does nothing, open Chrome's ⋮ menu and choose Install app
or Add to Home screen.
On iPhone, use Share → Add to Home Screen.
Working with no signal
The app copies itself onto the phone the first time you open it signed in —
every screen, the calculation engines and the equipment catalogues. After that it opens and
calculates on site with no signal at all. Anything you save while offline is held on the
phone and goes up the moment you are back in range.
Runs on its own in the background; this is only if you want to be sure
before you leave for site.