Getting data for app after installation

Hi, I'm doing an app which will work with some predefined images, but there are too many of them (more than 50MB), so I think it would be good idea to put them into Application.persistentDataPath.

But where should these images initially be? I mean for testing I could somehow get them where I need, but how is this done in case of professional apps that use separate data folder? Do you install apk, which after the first launch connects to some server and gets the data from there always? Is there some easy way to do that?