Unhappily it is not possible in cases in which we cannot have our application running on the server, what is the case with Dropbox, iCloud, Google Drive, etc.
You can use LiteSync with cloud services like AWS or Google Cloud or Alibaba Cloud for example. In this case you would have your server instance (in which you can install your software) running a simple application with the LiteSync library on it, as a primary node. Then the external, secondary nodes, would connect to the primary node on the cloud server. You can even try it using the free version of LiteSync (limit to 1 table).
Although I am not used with these cloud infrastructures, but I guess you need to build a docker image to deploy there.