Website at https://docs.aws.amazon.com/sdk-for-net.

Installation:

$ dotnet new console -o myApp

$ cd myApp

$ dotnet add package AWSSDK.S3 --version 3.3.110.19

Edit `Program.cs` to have the following contents (substituting `mybucket`, `<your access key>`. `<your secret>` with your information):

using Amazon.S3;
using Amazon.S3.Model;
using System;
using System.IO;
using System.Threading.Tasks;

namespace Amazon.DocSamples.S3
{
  class ListObjectsTest
  {
    private const string bucketName = "mybucket";
    private static readonly RegionEndpoint bucketRegion = RegionEndpoint.USEast1;
    private static IAmazonS3 client;
    public static void Main()
    {
      string accessKey = "<your access key>";
      string secretKey = "<your secret>";
      var config = new AmazonS3Config { 
        ServiceURL = "https://polycloud.crowdapis.com",
      };

      client = new AmazonS3Client(
        accessKey,
        secretKey,
        config
      );
      ListingObjectsAsync().Wait();
    }

    static async Task ListingObjectsAsync()
    {
      try
      {
        ListObjectsV2Request request = new ListObjectsV2Request
        {
          BucketName = bucketName
        };
        ListObjectsV2Response response;
        do
        {
          response = await client.ListObjectsV2Async(request);
          foreach (S3Object entry in response.S3Objects)
          {
            Console.WriteLine(entry.Key);
          }
          request.ContinuationToken = response.NextContinuationToken;
        } while (response.IsTruncated);
      }
      catch (AmazonS3Exception amazonS3Exception)
      {
        Console.WriteLine("S3 error occurred. Exception: " + amazonS3Exception.ToString());
        Console.ReadKey();
      }
      catch (Exception e)
      {
        Console.WriteLine("Exception: " + e.ToString());
        Console.ReadKey();
      }
    }
  }
}

Run the example*:

$ dotnet run

*You may have to add the following to `./bin/Debug/netcoreapp3.1/myApp.runtimeconfig.json`:

"configProperties": {
  "System.Globalization.Invariant": true
}