First, the honest part: an iPhone can't install an app file straight from Safari — Apple blocks that for every app, not just HERE. The free way in is a one-time setup with a tool called AltStore:
Install HERE with AltStore (free)
One-time setup — you need a Windows or Mac computer for this part:
On the computer, go to altstore.io and download AltServer. (Windows: also install iTunes and iCloud from Apple's website — not the Microsoft Store.)
Plug the iPhone into the computer with a cable. Open AltServer, choose “Install AltStore”, pick your iPhone, and sign in with your Apple ID. That sign-in is what stamps apps for your phone.
On the iPhone: Settings → General → VPN & Device Management → tap your Apple ID → Trust. Then Settings → Privacy & Security → Developer Mode → turn it ON (the phone restarts).
AltStore is now on the phone. Download the HERE app file from this page (the button above) — it saves into the Files app.
Open AltStore → My Apps → tap the + → pick the HERE file from Files. AltStore installs it. Done — HERE is a real app on your home screen.
Keeping it alive: free Apple accounts stamp apps for 7 days. AltStore refreshes them by itself when your phone and computer are on the same Wi-Fi with AltServer running — just leave AltServer open on the computer. If HERE ever says it can't be verified, open AltStore and tap Refresh All.
Tip: SideStore is a cousin of AltStore that refreshes right on the phone without the computer — same idea, slightly trickier setup.
Tap the Share button at the bottom of Safari — the square with an arrow pointing up.
Scroll down and tap “Add to Home Screen”.
Tap “Add” — HERE lands on your home screen and opens like a real app.
No file and no tools — HERE sits on your home screen and opens fullscreen. Same app, same everything.