Okay, I tried to create a workflow following https://piklist.com/user-guide/docs/building-workflows-piklist-v0-9-9/ and studying the Piklist demo add-on. Didn’t get much further.

My test files create one workflow (Test Workflow) with 2 tabs (First & Second). The First tab has two fields; Second has one. See the uploaded result.

The Settings page definition is lifted from Piklist Demos with minor changes:

add_filter('piklist_admin_pages', 'my_test_admin_pages');
function my_test_admin_pages($pages)
  {
    $pages[] = array(
      'page_title' => __('My Settings', 'piklist')
      ,'menu_title' => __('My Settings', 'piklist')
      ,'capability' => 'manage_options'
      ,'sub_menu' => 'edit.php?post_type=page'
      ,'menu_slug' => 'my-settings'
      ,'setting' => 'my_settings'
      ,'menu_icon' => plugins_url('piklist/parts/img/piklist-icon.png') 
      ,'page_icon' => plugins_url('piklist/parts/img/piklist-page-icon-32.png')
      ,'default_tab' => 'First'
      ,'single_line' => true
      ,'save_text' => 'Save these settings'
    );
    return $pages;
  }

Workflow header file and two tab files in parts/workflows:

/*
Flow: Test Workflow
Page: my_settings
Header: true
Position: edit_form_after_title
*/

/*
Title: First
Order: 10
Flow: Test Workflow
*/

/*
Title: Second
Order: 20
Flow: Test Workflow
*/

And then there are three files in parts/settings:

/*
Title: First Tab, Field 1
Order: 10
Tab: First
Setting: my_settings
Flow: Test Workflow
*/

  piklist('field', array(
    'type' => 'text'
    ,'field' => 'text11'
    ,'label' => __('Tab 1, Field 1', 'piklist-demo')
    ,'attributes' => array(
      'class' => 'regular-text'
    )
  ));

/*
Title: First Tab, Field 2
Order: 20
Tab: First
Setting: my_settings
Flow: Test Workflow
*/

  piklist('field', array(
    'type' => 'text'
    ,'field' => 'text12'
    ,'label' => __('Tab 1, Field 2', 'piklist-demo')
    ,'attributes' => array(
      'class' => 'regular-text'
    )
  ));

/*
Title: Second Tab, Field 1
Order: 10
Tab: Second
Setting: my_settings
Flow: Test Workflow
*/

  piklist('field', array(
    'type' => 'text'
    ,'field' => 'text21'
    ,'label' => __('Tab 2, Field 1', 'piklist-demo')
    ,'attributes' => array(
      'class' => 'regular-text'
    )
  ));

What am I missing here? Thanks for any help!

Donna