Email auto-respond to signing waiver form

I am part of a non-profit organization raising funds for the construction of a floating sauna in northern Canada. The sauna is free-use and not monitors by any staff. The goal is to automatically send users by email an electronic padlock combination to open the sauna door once they have entered their name, email address, and have agreed to the terms & conditions on our online waiver form.

These agreements are currently being logged in a database. To confirm the identity of the person signing the agreement, the user must acquire the electronic padlock combination from their email address.

I am aware that there are methods to auto-respond an email, but I want to auto-respond to a database entry. The auto-response would be sent to the email address entered into the email address text box.

Here is our waiver form: https://www.yksaunaproject.com/waiver-form