Link-Block: How to get Value for the URL-Attribute from Collection-Field?

In my Assets I have a folder called “pdf” with alot of pdf-files inside.
In a collection-field I save the relative path to those pdf-files in that folder.
Fieldname: “pdf-path”
Value: “/pdf/a11.pdf”

On the frontend I would like to display the collection as a list.
Within the Collection-Item I would like to place a Link-Block with the URL-Attribute containing the value of the field “pdf-path”.
But Webflow doesn’t let me choose the pdf-path-field. I only can choose fields type of URL. But they are useless to me, because they are absolute not relative paths.

How can I get the value from pdf-path-field and use is it a relative path in a Link-Block?

Kind regards