Android Paypal user login using sdk

I want to give cahsback/payout to user to there paypal account from app.

Unable to find login or user registration part in SDK documents.

Was able to find article https://www.sitepoint.com/implement-user-log-paypal/

Also in sample app on github https://github.com/paypal/paypal-here-sdk-android-distribution login is demonstrated using webview also not sure it is user login or merchant login.

How can I exactly implement user paypal login in my app and give user cashback?

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