Start by downloading the Unity Hub software and install the latest Unity version. Create a new blank project and choose the rendering pipeline that suits you best.

Get the Flow Core package from the Unity Asset Store following the link below:

Once you have purchased it, click on the “Import” button on the website and the Unity Editor’s Package Manager window should appear with the Flow Core package selected. Click on Download and Import afterwards.

Let the process complete and if everything went fine, your console shouldn't have any errors. If you do, please feel free to reach out to Bug Report