I'm not sure how accurate that forum thread/post is since it was written in 2014, but I'm pretty sure it's referring to our torstorm service provided via https://torstorm.org/
, which is a different thing than our transparent .onion access we provide to VPN clients.
Torstorm is a free service provided for the public, and works the same as any other onion2web service.
You would use it by replacing (using the DuckDuckGo .onion for example) http://3g2upl4pq6kufc4m.onion/
A CS account isn't required to use the torstorm service.
The nginx/lua setup that powers it does a few extra things to help keep users anonymous, like randomly changing everyone's user agent, and automatically removing any JS code that looks like it's trying to exploit the WebRTC vuln, no logging, and some other stuff that I'm probably forgetting.
It's different than the transparent .onion access CS provides, which is a feature that we don't really have a name for.
With torstorm, you get access to .onion sites from the clearnet.
With the transparent .onion feature, the request goes from you to the Tor instance running on the VPN server via the VPN tunnel, which means it doesn't involve the clearnet.
It's a little more secure/anonymous than using Tor directly on your own system (much faster too), but it does require a degree of trust towards CS because it puts us in a position where we could monitor your .onion traffic if we chose to (we never will, but there's no way for us to prove that we're not doing that).
If a customer doesn't want to use the service but still needs to access a .onion site while on CS, using Tor Browser would be the easiest way.
The transparent .onion feature uses what's basically DNS hijacking in order to redirect all .onion hosts to an IP in the 10.99.0.0/16 range (set by our server-side Tor's "VirtualAddrNetworkIPv4 10.99.0.0/16").
So as long as you set Tor Browser (or whichever browser you use) to send DNS requests to the socks server your Tor instance is running, then the CS transparent .onion feature will be unable to see your DNS request and change it to our Tor instance.