How to show the content of a group on the group page when using the Group module?
To show the content of a group, you need to create a view. The Group module provides Views 'relationships' to any node's parent group.

With that, these are the steps required:


Create a view about content.
Add a relationship to the parent group.
Add a contextual filter on the group's id (gid).
Create a page, a block, a content pane, etc (whatever fits your needs).


Below is an export of a (simplified) view created (in Drupal 7) using the steps described above:

$view = new view();
$view-&gt;name = 'group_content';
$view-&gt;description = 'Show all nodes that belong to a specific group';
$view-&gt;tag = 'default';
$view-&gt;base_table = 'node';
$view-&gt;human_name = 'Group content';
$view-&gt;core = 7;
$view-&gt;api_version = '3.0';
$view-&gt;disabled = FALSE; /* Edit this to true to make a default view disabled initially */

/* Display: Master */
$handler = $view-&gt;new_display('default', 'Master', 'default');
$handler-&gt;display-&gt;display_options['title'] = 'Group content';
$handler-&gt;display-&gt;display_options['use_more_always'] = FALSE;
$handler-&gt;display-&gt;display_options['access']['type'] = 'perm';
$handler-&gt;display-&gt;display_options['cache']['type'] = 'none';
$handler-&gt;display-&gt;display_options['query']['type'] = 'views_query';
$handler-&gt;display-&gt;display_options['exposed_form']['type'] = 'basic';
$handler-&gt;display-&gt;display_options['pager']['type'] = 'full';
$handler-&gt;display-&gt;display_options['pager']['options']['items_per_page'] = '10';
$handler-&gt;display-&gt;display_options['style_plugin'] = 'table';
$handler-&gt;display-&gt;display_options['style_options']['columns'] = array(
  'title' =&gt; 'title',
);
$handler-&gt;display-&gt;display_options['style_options']['default'] = '-1';
$handler-&gt;display-&gt;display_options['style_options']['info'] = array(
  'title' =&gt; array(
    'sortable' =&gt; 0,
    'default_sort_order' =&gt; 'asc',
    'align' =&gt; '',
    'separator' =&gt; '',
    'empty_column' =&gt; 0,
  ),
);
/* Relationship: Content: Parent group */
$handler-&gt;display-&gt;display_options['relationships']['parent_group']['id'] = 'parent_group';
$handler-&gt;display-&gt;display_options['relationships']['parent_group']['table'] = 'node';
$handler-&gt;display-&gt;display_options['relationships']['parent_group']['field'] = 'parent_group';
/* Field: Content: Title */
$handler-&gt;display-&gt;display_options['fields']['title']['id'] = 'title';
$handler-&gt;display-&gt;display_options['fields']['title']['table'] = 'node';
$handler-&gt;display-&gt;display_options['fields']['title']['field'] = 'title';
$handler-&gt;display-&gt;display_options['fields']['title']['label'] = '';
$handler-&gt;display-&gt;display_options['fields']['title']['alter']['word_boundary'] = FALSE;
$handler-&gt;display-&gt;display_options['fields']['title']['alter']['ellipsis'] = FALSE;
/* Sort criterion: Content: Post date */
$handler-&gt;display-&gt;display_options['sorts']['created']['id'] = 'created';
$handler-&gt;display-&gt;display_options['sorts']['created']['table'] = 'node';
$handler-&gt;display-&gt;display_options['sorts']['created']['field'] = 'created';
$handler-&gt;display-&gt;display_options['sorts']['created']['order'] = 'DESC';
/* Filter criterion: Content: Published */
$handler-&gt;display-&gt;display_options['filters']['status']['id'] = 'status';
$handler-&gt;display-&gt;display_options['filters']['status']['table'] = 'node';
$handler-&gt;display-&gt;display_options['filters']['status']['field'] = 'status';
$handler-&gt;display-&gt;display_options['filters']['status']['value'] = 1;
$handler-&gt;display-&gt;display_options['filters']['status']['group'] = 1;
$handler-&gt;display-&gt;display_options['filters']['status']['expose']['operator'] = FALSE;
/* Filter criterion: Group: Group ID */
$handler-&gt;display-&gt;display_options['filters']['gid']['id'] = 'gid';
$handler-&gt;display-&gt;display_options['filters']['gid']['table'] = 'groups';
$handler-&gt;display-&gt;display_options['filters']['gid']['field'] = 'gid';
$handler-&gt;display-&gt;display_options['filters']['gid']['relationship'] = 'parent_group';
$handler-&gt;display-&gt;display_options['filters']['gid']['exposed'] = TRUE;
$handler-&gt;display-&gt;display_options['filters']['gid']['expose']['operator_id'] = 'gid_op';
$handler-&gt;display-&gt;display_options['filters']['gid']['expose']['label'] = 'Group ID';
$handler-&gt;display-&gt;display_options['filters']['gid']['expose']['operator'] = 'gid_op';
$handler-&gt;display-&gt;display_options['filters']['gid']['expose']['identifier'] = 'gid';
$handler-&gt;display-&gt;display_options['filters']['gid']['expose']['required'] = TRUE;
$handler-&gt;display-&gt;display_options['filters']['gid']['expose']['remember_roles'] = array(
  2 =&gt; '2',
  1 =&gt; 0,
  3 =&gt; 0,
  4 =&gt; 0,
  5 =&gt; 0,
  6 =&gt; 0,
);

/* Display: Page */
$handler = $view-&gt;new_display('page', 'Page', 'page');
$handler-&gt;display-&gt;display_options['path'] = 'group-content';