How do I download the file so I can use it in my project.

Hi Michel, if the product you are looking at has BIM/CAD files available, then you will be able to see a 'Download' function on the right-hand side. If it doesn't have that, you will have to find a different product.
When you're doing a search, you can use the Formats filter to only see products that have the file type you are looking for. Let me know if you have any questions on how to use that function.