Adding zip archives to the Document File Type
If I understand correct and it is only an interface / layout issue, I suggest creating a view of that file with views and then put it in a block under the node and filter the block with content type and/or node conditions (or to put the block inside a paragraph layout piece).

If you mean you want the zip files to be in the also considered by Drupal as a Document file type so it would appear together with the PDF than what I suggest is to see how the module you use categorizes PDF files and then initiate this same code-level categorization to the PDF, for example, by adding the file extension PDF to the list of allowed extensions if there is one.