Generally the short answer is that you don´t transfer data🙂
When you build apps, you decide what an app does or how it looks, how access is managed etc. These are structural definitions. Data added to running r3 instances is not part of an application structure - it is therefore not exported.
There is one exception: Presets. This is data that is required for your application to run correctly and is part of the application itself. Presets are exported with the app.
When you want to migrate a r3 instance, like when moving a test or production instance, you do not export a new application structure, you dump the database and restore in your target environment.
