Just to be clear, you are saying the file application/config/site_install.php is actually there and not missing?

It is missing.The file does not exists.

so when you uploaded the files, the upload probably didn't complete.

That's a common issue when uploading Concrete5 unzipped.

The best way of doing it is to upload the zipped archive and use your cPanel - or whatever management interface your host provides you with - to unzip the archive right on the server.

Just replacing the missing file probably will not work as you may have more than one file missing, some of which you'll discover only after installing.

So I suggest you delete the whole thing, upload the zip, unzip it on the server and only then try to install.

I did that in the exact way for first time. Downloaded the zip file uploaded it using filezilla(ftp) and using command prompt unzipped it in the server location.

I have unzipped the folders locally and checked actually the file does not exist. I think it gets generated during the installation process. While checking i found that other folders and files are generated during the error stopped installation , which are actually not present in the downloaded c5 installation folder.

Found the solution while installing if you choose database. Instead of default handler in installation setting, the installation finishes smoothly

Thanks for the information.