Oh, the EFF is responsible for Certbot and they no longer support it running on Windows.
See: Certbot Discontinuing Windows Beta Support in 2024
Various alternatives are described there. The most popular are:
- Certify the Web (gui)
- Posh-ACME (powershell)
- simple-acme (cli) (as replacement for win-acme)
Yeah, pretty sure you need to be using an RSA cert. I think that version of Certbot defaults to ECDSA. So, you need to specify --key-type rsa. I am not sure what key-size is appropriate for those older systems. See the Certbot docs for defaults.