There was a point where acme.sh [1] changed their default from LetsEncrypt to ZeroSSL and that bit my automation because I only use wildcard certificates. ZeroSSL does not offer free wildcard certs [2] whereas LetsEncrypt does.
“By using ZeroSSL's ACME feature, you will be able to generate an unlimited amount of 90-day SSL certificates at no charge, also supporting multi-domain certificates *and wildcards*. Each certificate you create will be stored in your ZeroSSL account.”
[Edit] I remember now what led me to this conclusion. The error said I needed an account. I looked at the pricing page which indicated I had to pay for wildcards so I immediately looked for the flag to change back to LE. Looking at the pricing page I would still reach this conclusion. There should be some text that makes it obvious that using ACME allows for free wildcards.
I am not sure if this is an oversight or done on purpose..