Hi there! I see you're looking to download the MiniChat app on your iPhone running iOS 18.7. Let me help you with that.

Since you're using an iPhone, the best way to get MiniChat is through the Apple App Store. Here’s what you can do step-by-step:

1. Open the App Store on your iPhone.
2. Tap on the search icon at the bottom right.
3. Type "Minichat" in the search bar.
4. Look for "Minichat – video chat, texting" which is a social network app with integrated video and text chat.
5. Tap the Get button to download and install the app.
6. Once installed, open it and follow the registration or login instructions.

If you don't find it in the App Store, it might not be available in your country yet or the app may have a different name. Let me know if you run into any issues finding it or installing it on your device.

Are you satisfied with this solution, or would you like me to assist further?