What are you trying to connect the Beer Engine to.
If connecting to a polypin or a cask that is below the Beer Engine then all you need is a bit of Silicon tubing between the 2.
If you are connecting from a keg to a Beer Engine then you would need a Demand valve in the system to prevent the beer being pushed out of the Beer Engine by the pressure in the keg. I think it is also worth having a Demand valve if the keg or cask is above the Beer Engine otherwise gravity could push the beer through the engine.
Also does your beer engine have a cooling jacket that you want to connect, if so these need to be connected to the recirculating lines on a Beer Cooler. I haven;t connected up my cooling jacket as it doesn't seem necessary.