How to redirect to the "Thank you for the order" page in WooCommerce with sending an email?

Question

WordPress

Good evening
I'm making a custom payment module for WooCommerce through a not very well-known bank. The bank asks, among other data, to send them the following field: Where in the value field should be the page to which the buyer will redirect in case of successful payment I do this:
<input name="SuccessURL" type="hidden" value="">

<input name="SuccessURL" type="hidden" value="https://site.ru/checkout/order-received/' . $data['order_id'] . '/?key=wc">

The user, of course, gets to this page, the order is created in the system with the status "Pending payment", but the email to the client that the order has passed is not sent. What am I doing wrong?
How to make the client receive a letter stating that the order has been received and successfully paid?