I also got stuck on the last step when I did this box. I ended up using this version of psexec.py
instead:
python3 /usr/share/doc/python3-impacket/examples/psexec.py administrator@10.10.10.27
If you’re wondering how I found it, on Kali type:
locate psexec.py
And then apart from your ~/impacket/examples
you will get all other versions of psexec
showing. I just tried them all until one worked.