That's just one of the few parts of making an executable script. The file permissions also need to be properly set. See linux set executable - Google Search for more info.
Hmm, looks like the contents of the .zip release file. A little bit too much permissions, as those files should not be world writable! Not sure why certbot is complaining about that though, weird! Let me investigate.
Hm, I can't reproduce it on my Linux system, maybe it indeed is an issue with WSL?
Perhaps someone with access to WSL can reproduce your issue.
Also, is there any reason for using WSL? As certbot is also available for native Windows and the NameSilo authenticator and cleanup scripts might also work on Windows (not sure, the Github page doesn't mention OS compatibility).
I wasn't really sure how to install certbot for windows, so I went ahead and used wsl. I had a closer look, installed certbot for windows, and the execution proceeded. However, now I have a new problem:
DNS problem: NXDOMAIN looking up TXT for _acme-challenge.domain.org - check that a DNS record exists for this domain
I can ask a new question, but from what I gather is that I need to create a TXT record with _acme-challenge for my domain, correct?
The purpose of the authenticator.py script is to do that. (And cleanup.py to remove the TXT record again once it isn't necessary any longer.) You might need to increase the waiting time.