It seems that the simple link for the download file that I have on the website is inactive and not working / allows the user to click it to download the file on the iPad.
File upload support is limited in iOS. Safari does not allow access to files in other applications, but since iOS 6 allows downloading images either from the camera roll or directly from the camera.
iPad is another thing that a regular laptop or PC. Thanks to apple boxing applications for security reasons. If you do not imprison him, you cannot and cannot access the file system.