Level of Difficulty: Beginner.

There are multiple ways to download files from Google Drive, some of which require authenticaton and others that require lots of code. Here’s the simplest way to download the files, provided you’ve got the right file url.
var url = "https://drive.google.com/uc?export=download&id=<file_id>";
var path = "<add temp file path where file should be downloaded>";
using (var client = new HttpClient())
{
using (var s = client.GetStreamAsync(url))
{
using (var fs = new FileStream(path, FileMode.OpenOrCreate))
{
s.Result.CopyTo(fs);
}
}
}
The above approach also works when writing to memory stream, instead of copying to a file stream, copy to a new MemoryStream variable.