Hi @meenal_shukla. It will depend on what version of Tableau they are using. There’s Tableau Desktop which is the version individual users can download to their computers or Tableau Server and Tableau Online which are both in the cloud. Server is typically for enterprises who want to share and control access of a group of users.
In any version of Tableau, a user can export a table to CSV manually. And they can of course manually upload it to the S3 bucket. But that is manual and would be only good for single use. Here is some information on how to manually export.
If they are looking to automate this on Tableau Server which is most generally the use case I have seen, they can use Tabcmd to automate the export. Here are some how to steps. This will allow them to setup an export schedule but will save the file to whatever computer they are using. They can then use another utility to load the file to the S3 bucket. Here is one example of a tool they can use.
Hope this helps!