That's what I like first thing in the morning - an archaeological dig!

That line is referring to "hi-res" images, which were removed from jAlbum with the release of version 15 in 2017.

However, Matrix development continued until 2020, and the last version still seems to work in jAlbum 40. Attached is Matrix 58, a version that was never released. The last released version was Matrix 57, but this final iteration was converted from using BeanShell scripting to using Groovy scripting.

It seems to work, and produces a usable album, though I haven't tried all of its options. But it's obsolete, not being fully responsive. The current skin that most closely resembles Matrix is Saturn. Give that one a try!