Unable to deploy BWSG, no plugins available to select

I am trying to deploy BWSG for a first time on a server where ProjectWise Server and ProjectWise Explorer are installed.

The deployment wizard stops at "Select plugins" step with messages "No plugins to select". 

• Is there newer BWSG setup guide? The one on the wiki was last time updated in 2014 (communities.bentley.com/.../web-services-gateway-setup-guide)
• Setup guide requires following prerequisites to be installed:
  • Bentley ProjectWise Explorer S3 (08.11.09.122) or SS4 (08.11.11.111) or SS4 RU (08.11.11.559)
  • Bentley eB Insight Director or Management Console 15.4.1.325 or 15.05.01.236.
• but I couldn't find them on the download page. Any advice how to proceed would be appreciated!