Paragraph 6d:
Convey the object code by offering access from a designated place
(gratis or for a charge), and offer equivalent access to the
Corresponding Source in the same way through the same place at no
further charge. You need not require recipients to copy the
Corresponding Source along with the object code. If the place to
copy the object code is a network server, the Corresponding Source
may be on a different server (operated by you or a third party)
that supports equivalent copying facilities, provided you maintain
clear directions next to the object code saying where to find the
Corresponding Source. Regardless of what server hosts the
Corresponding Source, you remain obligated to ensure that it is
available for as long as needed to satisfy these requirements.
This just means that it should have some user–visible page that describes the software and any open–source components it uses, and that this same page should offer a way to download their source code. If you use an open–source component but haven’t modified it, you can send your users to its own webpage to download it if you prefer, but if you have modified it then you have to allow them to download the modified code.