You will be introduced to the requirements as we move through the chapters. To get started, you need to have access to a browser so you can access the DartPad website and play with Dart code.
To professionally develop and publish iOS apps, you need a developer license (paid annually), a Mac, and at least one device to test the applications. All this is not strictly necessary for the purpose of learning Flutter, but it might be useful to you.
The entire installation process and the requirements of the Flutter environment are available on the official website (https://flutter.dev/docs/get-started/install), but do not worry: you can start with the bare minimum and install any extras only when necessary.