How can I link a dropdown item with PayPal payment?

Please refer to BIG NIGHT OUT form

I am not sure if I understand you correctly.

I checked the form https://www.jotform.com/70736342083252 and once the items are selected and "Go to Payment Page" is clicked, the form is submitted to Paypal page.

Let us know what exactly you are looking for, so we can guide you accordingly.