If your name fields are not displaying in the Divi optin forms after adding your ESP and lists, find the following CSS in your stylesheet:

.thrive-newsletter .et_pb_newsletter_form p:nth-child(3) {
    display: none;
}

And either remove it, or comment it out like this:

/*
.thrive-newsletter .et_pb_newsletter_form p:nth-child(3) {
    display: none;
}
*/