The current build worked just fine for me... I created this VB VM:
Installed just fine... I have other issues regarding using this with AD users over NFSv4. But that's another matter... My guess is that your ISO image may be horked.
The MD5 of my download:
a21aeb3d7c470958d0dba5a8693c69e3 *TrueNAS-13.0-U4.iso