Use -dev version of nodeaccess_userreference

That module is up to 3.9 now and works with Entity Reference. Updated the drupal-org.make file to use the latest version, in commit e3665f8.

Are you getting an error when trying to install Drupal Ladder? Something like: "You need a module to reference users. Use either Entity references or References."

You are not alone, but we also don't know yet how to fix it.

This error is caused by the requirements check in the Node access user reference module. Basically, before it can be enabled it checks to see if the Entity Reference or Reference module is enabled, but during the install process, nothing is enabled yet, so it always fails. I have opened an issue on that module about it (and would love any ideas there): #1774488: Requirements check kills install profiles

In the meantime, you can hack your way around this. Modify the install file for that module, found at profiles/drupalladder/modules/contrib/nodeaccess_userreference/nodeaccess_userreference.install in your Drupal Ladder site. Find the nodeaccess_userreference_requirements() function, and change it to immediately return the $requirements array:

/**
 * Implements hook_requirements().
 */
function nodeaccess_userreference_requirements() {
  $requirements = array();
  return $requirements; // <--- ADD THIS LINE
  if (!module_exists('user_reference') && !module_exists('entityreference')) {
    $t = get_t();
    $requirements['user_reference'] = array(
      'title' => $t('User reference module'),
      'severity' => REQUIREMENT_ERROR,
      'description' => $t('You need a module to reference users.  Use either <em>Entity reference</em> or <em>References</em>.'),
    );
  }
  return $requirements;
}

That will bypass this requirements check and allow you to continue.