Hi,
Yes, it works in GB4.
To use it, you install it, including installing the AU (.component file).
Then open GB, open Info.
Normally, you would use it on your Master Track.
If so, click at the top of your Info, choose Master Track.
Click Details. Click on the top blank Effects window (just below Echo & Reverb), and select Ozone.
Click on the pencil icon on the far right of the Effects channel.
Try some pre-sets to start with.
It works well, but be aware that it's very demanding of processor power, so I'd recommend waiting to engage it until you're ready to create a Master Mix.
WH