Check out example codes for "download file from url asp net web api c#". It will help you in understanding the concepts better.

Code Example 1

var client = new HttpClient();
        var response = await client.GetAsync(@"http://localhost:9000/api/file/GetFile?filename=myPackage.zip");

        using (var stream = await response.Content.ReadAsStreamAsync())
        {
            var fileInfo = new FileInfo("myPackage.zip");
            using (var fileStream = fileInfo.OpenWrite())
            {
                await stream.CopyToAsync(fileStream);
            }
        }

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