@bhekiabstract Welcome to this community!
The error is objecting to the co.zw part of your domain name. I do not know why it would as it is included in the Public Suffix List.
But, the command you used is for the ZeroSSL Certificate Authority - not Lets Encrypt. That is the new default for acme.sh - see here:
You will need to ask ZeroSSL or at the github for acme.sh for reason for error.
OR, add --server letsencrypt to your command to issue a certificate with Lets Encrypt. If it continues to fail with that please post back here and we will help you.
Update: You might have success with Lets Encrypt. I just checked with Lets Debug and it gave no errors. I believe it would have if that domain is in some sort of US government restricted list.