Files are added in the ‚apps‘ tab of iTunes when you have your iPad connected (it should always be available if you’re synced with the iCloud). Scroll down the list of your apps to find the KronosRemote, then simply drag & drop your .pdf or .mp3 files to the files field. Press synchronize to transfer the changes to your iPad / wait for the cloud to sync, then your files should be available in the setlist slot editor.