The application through the Savi website is an income-driven repayment plan (IDR). This (typically) lowers payments for borrowers on their loan, as it is based on a debt to income ratio, family size, and tax filing status.
Most federal student loan borrowers are seeking Public Service Loan Forgiveness (PSLF). The reason the IDR is the first part of the Savi application is because this is the first step on the path toward PSLF. You can read more about PSLF Here: What is Public Service Loan Forgiveness (PSLF), and how do I know if I'm eligible?