Mail from Formular

I set up a mail form for my clients website. The Mails are sent, everything works fine. To archieve that I used my google mail account and had to enable the "2-step verification". So right now the emails are sent via smtp through my gmail.
But I dont want this mail adress to appear as sender. The reply-to adress should of course be the one from the form... how do I achieve that?

I added a screenshot so you can see my settings.

Do I need to use Sendmail as Mail Engine? Didnt get it running so far 😦