In order for Smartflo to communicate with Paypal, you will need to set up Paypal permissions.
Log into your paypal account.
Click the Tools drop down and select All Tools.
Find the Api Credentials item and click it.
Under the NVP/SOAP API Integration, click the Request API Credentials.
Select the Request API Signature and click the Agree and Submit button.
Click the Show links to display the API Username, API Password and Signature.