The Access 2003 Runtime is not downloadable. It was a Developer-level
separate purchase for all Office versions before 2007.
The 2007 runtime is supposedly free and downloadable, but its very new and
evidently very buggy.
Access Runtime (all versions), is intended to be developer-distributed and
used to run a fully developed Access application without buying Access at
retail. You can't create *anything* (files, forms, reports, data tables,
queries, code, etc.) with it, it has no user interface. If someone has
supplied you with a "fully developed Access app", then they can probably
supply you with the runtime as well. If you don't already have an app to
run, then Runtime won't do you any good: you can't do anything with it.
HTH,