You can read the actual tutorial here.
https://support.wix.com/en/article/corvid-tutorial-sending-an-email-on-form-submission
Also, this has been updated with the use of SendGrid API and SendGrid npm.
https://www.wix.com/corvid/forum/community-discussion/example-send-email-with-the-sendgrid-rest-interface
https://www.wix.com/corvid/forum/tips-tutorials-examples/example-send-email-with-the-sendgrid-npm-interface
In theory, the sendGrid.js and the email.jsw files in the backend are fine to be left as they are.
The only thing that actually changes is the page code with the dataset id name for the onAfterSave function and the form values.
Finally, note that SendGrid won’t send to certain emails and this has been added to the tutorial itself.
Important:
Using SendGrid to send emails from certain email providers may not work as expected. For example, see this notification about sending from Gmail addresses.