Get path of uploaded file inside a Twig template
Manage teaser Display : Change Format of your file field to Generic File From  admin/structure/types/manage/YouRContentType/display/teaser .
In your twig node--type--teaser.html.twig just print  {{ 
file_url(node.field_pdf.entity.uri.value) }} you will get the path to your file.
Note : As mentioned in comment it's uri Not url.