Unfortunately, there is no feature in Google forms to collect Payments. However, there are some alternatives you can try.
Enable Collecting form submissions to a Google Sheet
If not done already, enable saving the form submissions to a Google Sheet. The Google sheet will help you track the status of the payments (paid/pending)
Open your Google Form. Click on the “Responses” tab.
Collect responses to a Google Sheet.
In the responses tab, press the Google Sheet Icon to collect the responses to a Google Sheet.
Set up a link to collect payments
Provide that link in the Google Forms response page. Go to the settings box:
Go to the presentation tab and update the “confirmation message”. This message is shown after the user submits the form.
You will have to track the payments using the form's response Google sheet you set up in the previous step.
Follow up with unpaid users using Rapid MailMerge
There can be users who completed the form but couldn't complete the payment. You can follow up with those registrants through email. However, sending email one by one will be slow and inefficient. A better alternative would be to use the Rapid MailMerge add-on .
Using Rapid MailMerge, you can send emails directly from your Google Sheet. The best feature is, you can filter the Google Sheet and then send email only to those filtered results. This is handy when you want to send emails only to those who didn't complete the payment (Filter by payment status).
First, install Rapid MailMerge add-on.
Click the get add-ons link:
Install Rapid MailMerge add-on
Once installed, open Rapid MailMerge from the add-ons menu
Compose your email to registrants. Include your Paypal or Gumroad link in the email.