The mentioned PHP file is linked to the SD project. Open the file you downloaded from my site in SD, go to the tool panel and open the 'Inspector' pane. Then select the element 'form-container' and switch to the 'Element' pane. Then you should see how the PHP file is linked to the SD project. If you have - or create - the same folder structure as I have, you can't go wrong.

Don't worry so much about the Submit button. When the contact2.php has been correctly linked, and also when you have edited those three lines I mention on my page, the emails will know where to go.

Just to prove my point, here is a demo where I'm using the same component as you found in SD: https://eikweb.com/form/. I had to change it a bit to include an email field. You can test it. If you submit the form, it will come to me, but you should also receive an email summarising what you wrote.

After having submitted the form, you will be taken to my version of this form, to the page in my component collection.

For some reason the map of New York, which is included in the original CC component, didn't load for me. I guess it may be because the component is quite old (from SD version 2) and the map embedding code may have changed. I didn't bother with that, you'll probably want a map of a different location anyway.