In this article about the launcher there are two sections (one for iOS and another one for android) that can help you with this issue. They explain how to store your zip files inside your device.
http://support.ludei.com/hc/en-us/artic ... user-guide
If what you want is to use an external link, I recommend you to install node.js and create a local server using the command http-server in the folder where your zip file is stored. Then you can introduce the IP address in the launcher (i.e: MY_IP:MY_PORT/NAME.zip) and you don't need to upload the file once and again to dropbox.
You can download it from here: http://nodejs.org/
Hope this helps!