There is a solution to install the driver by hand, and this is how you do it:

Under the installation folder (c:\program files (x86)\fnatic gear\rush\ by default) there is a folder called "driver".  

In here there are two sub-folders, one x86 and one x64. 

Simply choose x86 for 32 bit OS or x64 for 64bit OS.

In these folders you have the driver.

Just run the dpinst.exe and you should be good to go. If the user doesn't know if his OS is 64 or 32-bit, just start with the x86 version. It will not install it if you have a 64-bit OS (or vice versa).