Is possible to display a document (not an image) from a collection?
Currently is is not possible.
Feel free to add a feature request here, we're really doing our best to improve.
I don't understand what for WIX offer the posibility of upload documents to a Collection if there is no way to use them (show in a page, download...)
Is possible display a document from database collection since your last post?
You can connect a table to the PDF file, so that once a site visitor clicks on the table, the PDF file is displayed.
If you wish to display the file itself on the page, it's impossible.