Develop a new PayPal plugin and use it as a step existing Visual Workflow

Introduction: I already have a public flow, public page and site in Salesforce. Here is the current location: [login to view URL] Of note, we have a Salesforce ENTERPRISE account At the end of the flow, I need the user to make a $30 payment via PayPal. Of note, we have a PayPal PROFESSIONAL account I'd like for this payment portion to be streamlined and all within the flow. Only if the payment has been received can the flow be completed. I believe (but not sure) I need a PayPal plugin to be built in SalesForce. Is that true? Other Notes: Sandbox recently refreshed. All work must be done in sandbox. Flow: residential rental application [login to view URL] Visualforce Page: tenant_rental_application: [login to view URL] Site: Apply: [login to view URL] PayPal Pro account already set up