Corina,

This theme relies on ACF to provide Theme Options. ACF is hidden from the dashboard to keep the interface clean and not confuse the users. As using the theme does not require the ‘Custom fields’ interface.

If you need it, you can enable it by inserting the following line to your functions.php (somewhere after line 115, or even better — in a child theme, so you don’t lose your modifications during a theme update): add_filter('acf/settings/show_admin', '__return_true');.
Please mind that the fields that the theme is using will not be in the ‘Custom fields’ interface as they come in php. However, you’ll be able to create your own fields.

Corina,

Storyteller is very plain and straightforward, its layouts are pretty simple and don’t require a page builder. I’m not sure I understand, what exactly you mean by getting the pictures arranged. However, if you mean doing something similar to what you see on the screenshot below, please know that the images are arranged automatically once you create a native WordPress Gallery (see the second screenshot).