Hello Sagar Agarwal,
I'm not familiar enough with the Alteryx solution to be able to chime in here but I know a number of our ambassadors and zen masters are familiar with the product. I'll link in Jonathan Drummey but be aware he is attending Tableau Conference next week and may not respond to this post. Have you posted this question in the Alteryx community as well? Let us know if you have found a solution.
I hope this helps.
I'm pretty sure that the schedule isn't available because the extract has no associated data source. It's Alteryx that is running a workflow to refresh the extract, at this time we can't have Tableau trigger Alteryx to refresh the extract. You'd need to use the Alteryx scheduler, Alteryx Server, or build your own batch script to do the extract refresh & republish operation.
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