If you have any version of Z3TA+ 2, this update is free for you. If you have Z3TA+ (classic) it's an upgrade available for purchase.
The "Load FX from another program" means you can load the FX from another program within Z3TA+ 2. There's no functionality to add
external VST FX into Z3TA+ 2, but you can work around that by simply bypassing the FX in Z3TA+ 2 itself, and then adding VSTs to the FX Rack on the Z3TA+ 2 track.