I think i do nothing special. I get the value from a field with the regular get_sub_field() function from a repeater. Than I store it into an array.
$field_value = get_sub_field($field_name);
//cut out module name to get pure field name
$field_name = str_replace($mod_name . ‘_’, ”, $field_name);
$field_output[$field_name] = $field_value;