how to download this component in rfa or rvt

Hi Vinodhini, unfortunately this product doesn't have any BIM/CAD files to download. Once you find a product with the right files, it is very easy to download them. You simply tick the 'Revit' option in the 'Download Files' section and then click on 'Download' underneath. A zip file will start downloading automatically and once you have unzipped this it is ready to use in your software.
The easiest way to make sure the products you are looking at have the right files is to do a search with the formats filter on. Here is a search that shows all Seating products with Revit files: www.modlar.com/search/products/furniture--seating/format--revit . I hope that helps!