I think that are some threads in the tech community, stating that webMethods 9.8 is not officially supported on Windows 10.
However I have installed the 9.9 trial version on such a system and the install worked.
Just make sure that you have admin rights when installing.
The problem that I faced was that the Designer libraries were not installed (due to the fact that I had no admin rights), so the Designer became…just basic Eclipse :).
I have browsed through the IS admin console and also wrote some services.
The IS part looks OK.
Just make sure when you tun the SAGInstaller jar to do it as an Admin → “run as Administrator”.
Hope this helps,