The Repeating Image Box widget requires a repeater field either on the current page, preview page(post etc) or on an option page. The supported subfields are text, textarea, wysiwyg and image.
Widget
You find it easiest by searching for ACF Repeating Image Box in the Elementor Search Widget … field:

Drag the following widget icon into your section to add the widget.

Settings

Select a repeater field and

The widget has 4 dropdowns that displays the corresponding ACF fields.
- Choose image lists image fields.
- Title lists text fields.
- Content lists textarea and wysiwyg fields.
- Link to lists URL and text fields.
Layout

Styling

Box

You have numerous settings for styling the box.

Header

You can decide if the text header should be above or below the image.
Image

Image is displayed using background image in centered cover mode.
Content

The styling of the description/content text is the standard settings with color, typography and so forth.