Hello Rakesh,
You can easily download the applications/softwares by searching on google. Various softwares will be available in full access while some of them will be available in trial period and you would need to pay in order to get full access. You can check the below mentioned links for the softwares:
CAD: https://www.autodesk.in/solutions/cad-software
STAAD: https://www.bentley.com/en/products/product-line/structural-analysis-software/staadpro
Revit: https://www.autodesk.com/products/revit/overview
All the best!
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