Use a web browser if the server is running IIS. If it's running an FTP server, you'll have to install an FTP client (see https://play.google.com/store/search?q=ftp client for a few of them). If it's running some other means of file transfer, we'd have to know what's available on it for file transfer.
And you'd need a PDF reader app on your phone (I've been using Foxit MobilePDF since before I got my Note 3.)