CocoonJS Launcher can execute ZIP files stored on a device. There's no need to upload them to Dropbox.
On Android, simply place the ZIP file in the root directory (not in a subfolder) of the device's SD card.
On iOS, you need to connect your device to a computer and launch iTunes. Then, switch to the Apps tab and select CocoonJS from the list. Scroll down to the File Sharing area and click the Add.. button to transfer the ZIP file to the device. Once that's done, click the Apply button to synchronize the device.