Did you try to install to another location? Looks like for whatever reason the install dir is locked. Re-booting might also be worth a try if you haven’t done that already.
BTW: Please report the false positive to BitDefender if you find the time for that. That would help us and possibly others greatly.
One general thing: The way this works in vorpX is not well suited for really large movements (standing up and running arounf will not work). This works best when being seated. Normal upper body movement (peeking around an egde, leaning into the scene etc.) should work fine.
I found the solution:
Even though Bitdefender wasn’t running, for some reason it kept the installer from moving the vorpControl.exe into the installation folder.
After uninstalling Bitdefender, it worked without any problems.