I downloaded the 9.4 Beta and tried to install it on 2 PCs. My 64 bit Windows 7 Professional machine seems to have taken it fine, but my Windows 10 Pro machine (also 64 bit) has an issue:
It had something to do with the firm's install permissions. Thinking I would need it, I asked an admin to run the installer initially and it failed. I then tried it "as myself" and it worked just fine (and required no admin rights, strangely).
Worked fine for me on a similar system. Try closing and opening again or downloading again. Sometimes these simple things can do.
@Marco_Boeck might suggest something here.