Integrating Aweber with PayPal

I am having a problem with setting up integration with paypal.
I) what is the best prgm or app/plugin for capturing email addresses?
2) what is the step-by-step way to set this up through the app to aweber?
3) I cannot find IPS info/link either on aweber or paypal.
I see you have to have an ISP link to paypal but I can’t find that link anywhere – either on awever or paypal

Any help is appreciated. Thanks.