For WP Multisite (subdomains), if you have your wildcard cert enabled in the main site, it will work automatically in your sub-sites.
For two individual sites (main and subdomain), you should request individual SSL certs for each site. Webinoly does not have support for this yet using wildcard certs. You can do it manually, requesting a wildcard cert for you main site and then setting this cert manually in your subdomain.
PayPal · GitHub Sponsors · Bitcoin