Files not synced to AWS S3

We are trying to integrate AWS S3 in our Kentico 10 application.

I followed this link:

https://docs.xperience.io/k10/custom-development/working-with-physical-files-using-the-api/configuring-file-system-providers/configuring-amazon-s3#ConfiguringAmazonS3-Medialibrarynotes

I created following module in App_Code => CMSModules => AWSS3 => AWSS3Module.cs

Here is the code of AWSS3Module.cs

using CMS;
using CMS.DataEngine;
using CMS.EventLog;
using CMS.IO;
using System;
using System.Collections.Generic;
using System.Configuration;
using System.Linq;
using System.Web;

/*
    Make sure following entries exists in web.config => <appSettings>

    <add key="CMSAmazonBucketName" value="" />
    <add key="CMSAmazonAccessKeyID" value="" />
    <add key="CMSAmazonAccessKey" value="" />

    <add key="CMSAmazonPublicAccess" value="true" />
    <add key="CMSAmazonEndPoint" value="" /> 
*/

[assembly: RegisterModule(typeof(AWSS3Module))]

/// <summary>
/// Summary description for AWSS3Module
/// </summary>
public class AWSS3Module: Module
{
    public AWSS3Module(): base("AWSS3Module")
    {
        //
        // TODO: Add constructor logic here
        //
    }

    // Initializes the module. Called when the application starts.
    protected override void OnInit()
    {
        base.OnInit();

        // Assigns a handler to the Insert.After event for OfficeInfo objects
        EventLogProvider.LogInformation("AWSS3 module", "OnInit", "This code is running");

        // Creates a new StorageProvider instance
        AbstractStorageProvider mediaProvider = new StorageProvider("Amazon", "CMS.AmazonStorage");

        // Specifies the target bucket
        mediaProvider.CustomRootPath = ConfigurationManager.AppSettings["CMSAmazonBucketName"];

        // Makes the bucket publicly accessible
        mediaProvider.PublicExternalFolderObject = true;

        // Maps a directory to the provider
        StorageHelper.MapStoragePath("~/Sitename/", mediaProvider);
    }
}

I read in one of the post that only new files will be synced. I tried adding few files in the media folder but nothing added in bucket.

There are no errors in logs. Also, I can see the module is loaded in the logs.

Bucket policy seems to be correct or I couldn't find issues in logs.

What am I doing wrong?

Also, if a file is uploaded, how can I get the S3 URL for that file?