1. Conduct market research: Before developing the app, conduct market research to understand the needs of your target audience and identify your competitors. This will help you to determine the features and functionalities that you should integrate into your app.

2. Decide on the platform: Decide whether you want to develop a native app for iOS, Android or b, or both platforms, or use cross-platform development tools such as React Native, Flutter, or Xamarin.

3. Design the app: Hire a UI/UX designer to create an intuitive and user-friendly design for the app. Make sure that the design is consistent across all platforms and devices.

4. Develop the app: Hire experienced developers who can create a robust app with all the necessary features such as user registration, store and product selection, payment gateway integration, order tracking, and more.

5. Test the app: Test the app thoroughly to identify any bugs or issues that need to be fixed before launching it. Perform different types of testing such as functional, performance, and security testing.

6. Launch the app: Once the app is tested and ready to go, submit it to the respective app stores for approval. After approval, launch the app and make it available for download.

7. Promote the app: Market the app aggressively using social media, influencer marketing, and other digital marketing strategies to attract users.

8. Maintain the app: Ensure that the app is maintained and updated regularly to fix bugs and add new features based on user feedback.

Creating an Instacart clone app can be a complex process, but by following these steps, you can ensure that your app is developed successfully and meets the needs of your users.