Using the linked_field module and the [paragraph:field_pbpresentation_file:entity:url] token, I get the edit link for the media entity, not the link to download the file itself.
What token should I use for the download link?
You probably want the URL of the file entity, not the media entity.
You have to find out the field name of the file field in the media entity. If you are using a core preinstalled media type it could be for example field_media_file. Then you can access the file entity and the URL:
[paragraph:field_pbpresentation_file:entity:field_media_file:entity:url]