Load atlas data to android

Please. I’m developping an app working with realm sync and need some explainations for two worries…

1- I’ve inserted most data that will be used by the user in the backend .
When the user first load the android app, no data is in the application.
Now, when he enter other login data like phone number and statut, I want those data to be sync to him.
How can do it please?

For the moment, when I try doing so, the server send an error empty ‘partition value’.

2- In the same app, I’m working with embeded documents. How can I manage partition value for these documents??

Thanks !!