Further to TIm's advice the Communications Bridge (CB) is still 32-bit and you will need the 32-bit client for the Microsoft Host Integration Server
The CB has been tested with Microsoft Host Integration Server 2010 and its 32-bit client running on 64-bit OS.
For later HIS versions e.g. installed on a Biztalk Server, you would have to rely on Microsoft upward compatibility
P.S..
The 8.5 Tech Reqs are now available in the Gen 8.5 Wiki Release Information section.
https://wiki.ca.com/display/GEN85/Third+Party+Software+Version