The Disks and Tapes files are in the /readwritefs/ directory! You may need to go up twice in the directory structure to find this directory.
Remember to save snapshots, tapes and dsk in this directory as it is the only one that is saved in your browser's storage space.
In order to download one tape or dsk file so that you can use it in an emulator on your computer first click on this button and then on the name of the file