Well, transfering multiple files most likely means to zip/tarball them together at the server side. But unpacking an archive after downloading it on a mobile OS

Well, transfering multiple files most likely means to zip/tarball them together at the server side. But unpacking an archive after downloading it on a mobile OS needs a number of clicks (and an unpacking app), which is cumbersome. In the end, it is probably about a client endpoint for your tool.