following this process, i found that I needed to firstly run the fw1884.exe to put the installers on to the hard drive
 
then I needed to open the sound control panel and moving through to drivers, manually install the drivers from the location on the hard drive before it worked.
 
one step missing from the above, but it is now working thanks to some lateral thinking (need to manually install the drivers after installing to the drive with a fail to install because the drivers will not work in win 10)

My FW1884 is still going strong. I am only using it as a Control Surface.
I have a copy of the Legacy FW driver needed, just in case Win decides to wreck it.
It haven't happened yet
 

Geez, I'm running some FW Motu's on a bog-standard Win10 machine with an aftermarket FW card a I never had to install no steenkin' "legacy" driver... 

possibly because motu is keeping their drivers up to date unlike tascam
 
getting the fw1884 to work is only one step within many of tricking out this "new" old machine (Dell t7500)
 
currently in the process of dealing with reason 10's new method for initial authorisation (you cannot activate your ignition key until you run it once via internet authorisation, even if you never want to do that again) and downloading another 7GB of content that they do not ship with the installers SMH at some companies arrogance