Can USB Disk send files to another app?
USB Disk has the ability to send files to any app that accepts files. To know if an app accepts a file, you need to try to send a file to it. Make a long press on the name of a file in a list of files and choose "Open with app...". If the other app appears in the list, press on its name to send the file to it. If it does not appear in the list, you need to contact the makers of the other app to ask them to add the ability to receive files from other apps.