Link to a FTP VS link to a LMS

Hi!

If one uses different LMS for identic copies of a course, for example:

• One version published on a LMS (Docebo) of "ones own organisation":
  "organisation A" (where members can access the course).
• Copies of the same course published on several other clients (unknown) LMS:s:
  "organisation B, C, D and so on (where employees have access to the course whithin their own organisations LMS).

Add then the need of linking to a PDF owned by organisation A showing one or several pages of text.

Question: how/where would you publish the PDF to make sure that all the different users can open the PDF?

Add the perspective of unknown firewalls, no need of tracking who downloaded the document - but a smooth/safe way for all the above to reach the document over time?