Your Paypal ID is the email address registered on your paypal account.

If you have ever made a payment by paypal, you will probably be familiar with this as you will have been asked to input your paypal email address and then your password.

To be paid by paypal, you need to tick the checkbox entitled: Pay Via Paypal? 
This checkbox is on the application form for our affiliate program. It is also available once you have signed up and been approved as an affiliate, in your control panel.
You can change your method of receiving your payments to Paypal any time by ticking the checkbox, inputting the email address to which your paypal account is registered, and then clicking to save your changes.