Another solution not mentioned is to use a different DB engine just for storing the PDFs as Blobs ...probably Firebird.
So no more chasing folders.
In the proposed solution i would modify it like this
Table :
ID User(PK) Application (PK) File (PK) Location SaveActionDate
AutoNmbr Number Number Number Text Date
So for every save action you log which user from which application saved the particular PDF to which location and when.
I assume that your PDFs have some kind of uniqueness so the exact filename would be saved them to a separate table. (ID, FileName)
This works for me. The conn string is rarely changed once the app is deployed but allows me, or a user, to change it if necessary.