I downloaded 1.1.5, and I uploaded everything from the package except the “albums” folder, the “cache” folder, and the “/themes/default” folder (because I modded it).

But when I’m in the admin panel, the bottom right corner still says 1.1.3
Did it work? What did I do wrong?

You need to run zp-core/upgrade.php

Bingo. Done.

...DANG it's fast!