the command in the section "Get a certificate using SSL" needs a space between openssl and req.
existing: opensslreq -newkey rsa:4096 -sha512 -nodes -keyout ztna.key -new -out ztna.csr -config mytemplate.txt
with space: openssl req -newkey rsa:4096 -sha512 -nodes -keyout ztna.key -new -out ztna.csr -config mytemplate.txt