Example of how to use Caldera Forms Connected Forms hooks to send an email with a link to continue the form sequence. See - https://calderaforms.com/doc/connected-caldera-forms-hooks/

connected-forms-email.php

/**
 * Send an email to the person who has filled out the first form in a Caldera Forms connected forms sequence with a link to continue.
 */
add_action( 'cf_form_connector_sequence_started', function ( $form_id, $entry_id, $user_id ) {
	//change this to the URL that your form is on
	$url = 'https://hiroy.club/sign-up';
	//add cfcf-id query var with user identifier
	$url = add_query_arg( 'cfcf-id', $user_id, $url );

	//Change this to the ID of the field with the email address - MUST be in frist form of sequence
	$email_field = 'fld_7474165';
	//Change this to the ID of the frield with name -- Must be in first form of sequence
	$name_field = 'fld_9697545';

	//Get all submission data
	$data = Caldera_Forms::get_submission_data( $form_id );

	//get email and name
	$to   = $data[ $email_field ];
	$name = $data[ $name_field ];

	//Change your email message
	$subject = 'Thanks for starting the application form';
	$body    = 'Hi ' . $name . '. You can go back to this form at any time. Just use this <a href="' . $url . '">link</a>';
	$headers = array( 'Content-Type: text/html; charset=UTF-8' );

	wp_mail( $to, $subject, $body, $headers );
}, 10, 3 );


/**
 * Change which Caldera Forms connected form sequence data is loaded based on a query variable
 */
add_filter( 'cf_form_connector_position_data', function ( $data ) {
	//check for query var
	if ( isset( $_GET[ 'cfcf-id' ] ) ) {
		//Could be a user ID
		if ( is_numeric( $_GET[ 'cfcf-id' ] ) ) {
			//is this the right user?
			if ( get_current_user_id() === $_GET[ 'cfcf-id' ] ) {
				//nope, make them log back in
				auth_redirect();
			}
			//see if we have progress in user meta
			$_data = get_user_meta( get_current_user_id(), CF_FORM_CON_SLUG, true );
			//yes we do, so use it.
			if ( ! empty( $_data ) ) {
				return $_data;
			}
		} //could be cookie ID
		elseif ( is_string( $_GET[ 'cfcf-id' ] ) ) {
			//see if we have tracked data
			$_data = get_option( 'cfcfrm_' . $_GET[ 'cfcf-id' ], array() );
			//yes we do, so use it.
			if ( ! empty( $_data ) ) {
				return $_data;
			}
		}

	}

	return $data;


}, 10 );