Note that Whonix 17 (the Xfce version you’re probably talking about) is end-of-life and no longer supported:
You may, however, be able to build the last released version from source:
It’s unlikely that you’ll get much help with this process here since it’s end-of-life, but you can try to build it anyway.
To avoid the potentially critical security and privacy risks associated with using EOL software, it is highly recommended that you use Whonix 18 instead: