Creating server for android app

Im want to create a server for my android app, the server should download a zip file from a static url (every night). The zip file contains fiew txt files in csv format, the files data should update an sqlite db and the android app should get data from the db. The server need to be secured to some degree and only allow requests from the app. Im a server newbie and work with java. What would be the easyest way to start? Ive read about parse.com but it cant handle file downloads, Google cloud platform seems appropriate but Im not sure about the pricings. What are my options ? Also please add tutorials