No, people use this with Apache and nginx etc fairly regularly. The auto discovery thing only knows about IIS and is using the IIS site selected in the first tab dropdown. As you are not using IIS for this site you should probably set that to “No Site Selected” and manually provide the domains.
The test can fail locally if the local machine is unable to resolve that URL (even if the URL is publicly accessible), so the real test is still to use Request Certificate.