To clarify, Google App Engine is a fully managed serverless platform provided by Google Cloud Platform (GCP) for building and deploying web applications. It allows developers to focus on writing code without worrying about infrastructure management.

You do not need to download Google App Engine itself since it is a cloud-based service. However, you can download and set up the necessary tools to interact with Google App Engine on your local development environment. Here’s a general outline of the steps you can follow:

1. Install the Google Cloud SDK: The Google Cloud SDK provides command-line tools and libraries for interacting with GCP services, including Google App Engine. You can download the SDK from the official Google Cloud website (cloud.google.com/sdk) and follow the installation instructions for your operating system.

2. Authenticate with your Google Cloud account: After installing the SDK, you’ll need to authenticate with your Google Cloud account. Run the gcloud init command in your terminal, and it will guide you through the authentication process, including selecting your Google Cloud project.

3. Install the necessary programming language dependencies: Depending on the programming language you are using for your App Engine application (such as Python, Java, Node.js, etc.), you might need to install specific dependencies and frameworks on your local development environment. Refer to the respective language documentation or the Google Cloud documentation for specific instructions.

4. Set up your local development environment: Create a new directory for your App Engine project and set up your development environment. This involves creating and organizing your application code, configuration files, and any required dependencies.

5. Develop and test your application locally: With your local development environment set up, you can now write your application code and test it locally using the appropriate development server or tools provided by the programming language or framework you are using.

6. Deploy your application to Google App Engine: Once you have developed and tested your application locally, you can deploy it to Google App Engine using the command-line tool gcloud app deploy. This will upload your application to the App Engine service, where it will be hosted and made available.

Remember that the specific steps and commands may vary depending on the programming language and tools you are using. It’s recommended to refer to the official Google Cloud documentation for detailed instructions and examples tailored to your specific use case.