The File type field allows creating a field for attaching the file to the listing.
Go to the Listing Types section and drag the created field into Used custom fields so that it appears during the listing creation process.
After saving the changes on Custom Fields, the File type field can be displayed in the next sections. Drag it to the appropriate locations.
In the listing creation process, the file should be attached to the File type field in order to display it on the listing.