How to get a delta value from a composite with ilimited values?

I have this webform with composite field where I add a file and a field where I add a number.

What I wish is using the token, to rename the file with number inputed in the number field. But the thing is I have a composite with multiple ilimited values and I can only do it if I declare a delta number as the following token: [webform_submission:values:element_key:delta:sub_element_key]

How can I do it programatically if it is possible?

Also, it's possible sum up composite multiple values using computed twig? As above, the delta seems the problem.

For the first part of the question I still have no clue, it might not be (only) the delta the problem as I could work around it using computed twig data, but the fact the attachment and the number field are inside the composite, what may create a looping error.

As for the second question, here what worked for me using the computed twig from webform:

SUM TOTAL OF THE COMPOSITE SUBELEMENT:

{% for item in data.composite_element_key %}
  {% set sum = item.subelement_key + sum ?? 0 %}
  {% if loop.last %}{{ sum }}{% endif %}
{% endfor %}

Thanks to https://craftcms.stackexchange.com/a/16445