Programmatically Create an Array of User Objects and Print in Twig Template
Before you can render a list of entities you have to build a render array:

$variables['userList'] = \Drupal::entityTypeManager()
  -&gt;getViewBuilder('user')
  -&gt;viewMultiple($userList, 'compact');


Now Twig is able to render the entities:

{{ userList }}    


You don't need |render, because Twig renders arrays automatically.