I'm trying to use the Medium module, but for some reason it just shows "placeholder" when I click on the Configuration > Content Authoring > Medium Editor. Could you point me to any solution for that?
That module has not been finished, yet. The function that should return the form for the settings of that module doesn't even allow to set any settings; it just output that Placeholder text you see.
$form = array(); // @TODO: Allow users to choose the image style used for media embeds. // @TODO: Allow users to choose which media plugins should be exposed. $form['whatever'] = array( '#markup' => 'Placeholder' ); return $form;
The module is in a alpha state; don't consider it ready for production.