I suspect if you are determined enough, you can
bypass driver code signing and install the Veracrypt driver anyway, though it won't be a pleasant experience
I had to do it once at work when a device we use had an unsigned driver, and the manufacturer is no longer around. So we had to use the trick above to force the driver to install on Win10 (that, or allocate another machine to run Windows 8 and deal with other potential issues down that route).
Thankfully, we found a replacement for that device later on and didn't have to deal with this issue since.