In this example, your ACF field is named ‘associated_image’ and ‘chosen-image-size’ is the desired image size that is set within your theme.
// Get particular category's object info.
$queried_object = get_queried_object();
// (Optional depending on desired outcome) If you wanted to get the type of taxonomy.
$taxonomy = $queried_object->taxonomy;
// (Optional depending on desired outcome) If you wanted to get the associated ID.
$term_id = $queried_object->term_id;
// Get image ID for this field.
$attachment_id = get_field( 'associated_image', $queried_object );
// URL of image at specific size.
$image = $attachment_id['sizes']['chosen-image-size'];
Additional reading:
- WordPress Codex: get_queried_object
- ACF Docs: getting values from a taxonomy field