If macOS cannot verify the developer, try opening LARPay, then go to System Settings → Privacy & Security → Open Anyway and confirm Open. You may be asked for your Mac password.
Install from Terminal
The command below downloads the DMG, verifies it and installs LARPay into Applications.
Open Terminal: press ⌘ Space, type Terminal, press Return.
Copy the command below, paste it into Terminal and press Return.
LARPay installs into Applications and opens by itself. If macOS asks for your keychain password, enter your Mac password and choose Always Allow.
Run the Terminal command above. LARPay installs into Applications and opens by itself.
Paste your license key and connect your iPhone with a cable.
Windows
Install iTunes (64-bit) from apple.com/itunes/download/win64. The Microsoft Store version (where apple.com/itunes sends you) doesn’t work; if you have it, uninstall it first. Then open the Books app on your iPhone once.
Run the installer. If “Windows protected your PC” appears, choose More info → Run anyway.
Paste your license key and connect your iPhone with a cable.
Open the installer. Launch LARPay. Paste your key.
The Mac app uses a local signature and has not been notarized by Apple. Manual approval may be required. The Windows installer is not yet signed. Device compatibility is still being tested.