add_action('formcraft_before_save', 'login_user_addon', 10, 4);

function login_user_addon($filtered_content, $form_meta, $raw_content, $integrations)
{
    global $fc_final_response;

    foreach ($raw_content as $key => $value) {
        if ( $value['label'] == 'Adres e-mail klienta' )
        {
            $user_email_login = $value['value'];
        }
        if ( $value['label'] == 'Hasło klienta' )
        {
            $user_pass_login = $value['value'];
        }
}


  $user = get_user_by( 'email', $user_email_login );

  $creds = array(

    'user_login' => $user->user_login,
    'user_pass'  => $user_pass_login

  );

    $usr = wp_signon( $creds, false );

    if ( !is_wp_error( $usr ) ) {
            wp_set_current_user ( $usr->ID );
            wp_set_auth_cookie  ( $usr->ID );
    } else {
        $fc_final_response['failed'] = $user_pass_login;
    }
}