Error @ :: Microsoft.SharePoint.Client.File.OpenBinaryDirect :: the property or field has not been initialized. It has not been requested or the request has not been executed. It may need to be explicitly requested

I am trying to download a document from SharePoint online using claims authentication. I could successfully get the context and able to view the list and list items. when I try

FileInformationfInfo = Microsoft.SharePoint.Client.File.OpenBinaryDirect(ctx, item["fileref"].ToString());

to open a specific document, I get the error "The property or field has not been initialized. It has not been requested or the request has not been executed. It may need to be explicitly requested".

Please help where can I go!

TIA