Dear Sajjad Salih,
The Dish Stirling model is available in SAM 2020.2.29:
sam.nrel.gov/download/version-2020-2-29-1.html
We are no longer maintaining or supporting the Dish Stirling model in SAM.
You can install and run more than one version of SAM on your computer, so you you can use the older version for Dish Stirling and the latest version for the other models.
Best regards,
Paul.