If you specifically need a version from the 3.0.x series (like 3.0.69), here is what you should know:
: You can download a trial version of the latest Newton from the official site. It is fully functional but usually limited by a restricted frame export.
: Get the .aex (Windows) or .plugin (Mac) files from your aescripts account.
Newton is currently on version 4, which is the 2D physics engine for After Effects that transforms layers into rigid bodies that react to gravity, collisions, and friction. Key Details for Newton 3.x