Hello! My name is Justin and I write for the Zapier blog. Let’s see if we can figure this out together.

I’m afraid the bad news is that Zapier can’t really cause something to happen in a user’s browser when they hit the Submit button in Google Forms.  What you could do is (for example) email a user with a link to your PayPal page, assuming they fill in their email address in the form. Does that make sense? 

Thanks for your quickly answer.

The thing is:

I’m doing a form for a restaurant and the menu have to be paid before sending the response of the form to the spreadsheet, you understand what I mean?

You’re approach is already done, but doesn’t work right for this issue.

Hello! Jpot is correct here in that Zapier can’t make something like this happen in the browser, but what I can suggest is that you use a form solution like Typeform or Jotform that allows you to take a payment at the end of the form filling process. 

https://www.typeform.com/

https://www.jotform.com/

https://www.formstack.com/

https://mailchimp.com/

These are all solutions that have (paid) functionality that will allow you to capture payment at the time of booking

There are also other ways you could do this using Google forms alone, but they would require a developer to set up a redirect to your payment platform. This can get a bit messy - So I wouldn’t recommend it, as I think you’d need to look for the form reloading and trigger a pop-up.

I recently built a small tool that can take payments with Google Forms. You can get it here as a gsuite addon. It’s a little different from what you asked as it requires someone to pay before clicking submit, but you can add it to the last page of a multi-page form if you want to make people complete every other question first. I built it so I could carry on using Google forms rather than having to try out a bunch of different form builders.