I had a similar problem where the silent install of directx9 failed. I went back to the 2017 CD and ran the directx setup, PreReqs>DirectX>dxsetup.exe. This runs it at user level. It ran successfully. I then ran the Solidworks install from the CD. It succeeded.
I'm struggling with my install along these lines as well, but running a standalone dxsetup.exe install doesn't work either. This is a Windows 10 VM on Parallels (both 12 and 13 have been attempted). I've successfully used SolidWorks on a Windows7 VM on the same laptop. But when I attempt the installer on my new VM, it seems to hang on DX. It's now 4 days after I started the installer, running continuously, and the DirectX install is 54% complete...! I also downloaded both the standalone and web DirectX installers from Microsoft and they won't run on my machine, hanging in the same way.
I believe DirectX 9 is already installed on my VM (all the files appear to exist in c:/Windows/System32/) so I wonder if it's possible to run the SolidWorks installer and omit the DX prereq install? If you've tried this, please let me know how it worked - I don't see the option to omit it.
Thanks in advance!