This is an example of the forms attachment plugin that I created for another project. It might work for you, but there’s no way to separate the downloads into groups like you have on the existing site. To use it, you upload documents to a page and put the the word “attachments” inside of [ square brackets ]. So in the content editor, you only see the code, but on the public page, it’s replaced with a list of all of the documents in the gallery for this page. If you want, I can remove the date and “type” fields as they don’t make much sense in this case. The “publish date” is a part of the database, not something you can change through the admin.