Adding Paypal as a Brand is required to sell your products on other partner stores.
If you are looking to setup as a Seller read this article instead.
Before you start:
1) Paypal Email: Signup for a paypal account to receive payments here
1) Go to settings in the Ally dashboard
2) Click the Brands Tab
3) Make sure the switch is turned on
4) Enter your paypal payout email
5) Click Save