This refers to a specific update in the game's lifecycle. In the world of strategy games, version numbers are critical because they track balance changes, AI improvements, and bug fixes. v1.0.64759 likely corresponds to a stable build released after a major DLC launch.
The use of a standard zip archive (rather than an installer like an .exe or an .iso ) suggests this might be a "portable" or "pre-installed" version. These are popular because they allow users to simply extract the folder and run the game without a complex installation process. A Word of Caution File: Old.World.v1.0.64759.Incl.ALL.DLC.zip ...
: Because this is a static zip of version 1.0.64759, it won't receive official bug fixes or new content released by Mohawk Games later. This refers to a specific update in the game's lifecycle