МОД: Клинок Армагеддона / Armageddon's Blade

I figured out the archive and the installation process.

However, in my game's root directory, it's not arranged as shown in the video. There are two more folders: Hammers of Fate and, accordingly, Tribes of the East. Installing the mod in either of these folders causes the game to malfunction.

This isn't the game's folder; it's a folder containing different games. Tribes of the East differs internally from the original, so it's stored separately.

Also, it's unclear why the archive contains a large "data" folder if only Waterfall_Armageddons_Blade.pak and index.bin need to be installed from it?

Well, the mod version is new, but the instructions are old. In the video, the "data" folder only contained two files, but now it includes everything needed for the game to function properly. It's best to delete your current "data" folder and download the entire folder from the archive.