I understand you're looking for a review of the (often referred to as the "SSL G Bus Compressor") and potentially a free download link.
If you are searching for a "free download" of this style of compressor, consider these legitimate free plugins that emulate the SSL G-series hardware: ssl gmaster buss compressor free download link
The by Waves Audio is a legendary piece of software, but it is not freeware . It is a paid plugin modeled after the center section of the SSL 4000 G console. SSL G-Master Buss Compressor I understand you're looking
: Often cited as the best free alternative to the Waves G-Master, this plugin accurately captures the SSL snap and punch. Acustica Audio - TAN : Often cited as the best free alternative
For anyone building a professional mixing toolkit, the SSL G‑Master offers an of vintage sonic character and modern workflow convenience—provided it is obtained through legitimate channels.