Can't help with the download location, but, no, your AC 14 key will not work with any newer versions. All old versions up through 14 will run with it. (Basically, any active license is a license for that version and all prior ones. There can be hardware and OS issues preventing really old versions from running though.)
In case someone else knows of a download link for you: what country specific version are you looking for?
One of the forum moderators
AC 28 USA and earlier • macOS Sequoia 15.2, MacBook Pro M2 Max 12CPU/30GPU cores, 32GB