Did you have to remove (offline) the drives in windows before they would be recognized? Also, do the drives need to be formatted in any special way before they can be attached?
I also seem to not be getting past the connection problem. Whether I use a bridge connection or not, synology assistant fails to correctly detect the VM's IP address. This only happens after it installs the software and says the DSM is rebooting. I get the grub 22 error causing me to shut down the VM, recopy the synoboot.vdi file and restart the VM. The synology assistant is still running during this time.