I can't tell you what/if you did anything wrong. There's just too many factors, some of which a highly subjective ("cultural fit"). I did interviews for my company too and usually we would optimize our process highly to get no false positives, even if that meant we had a few false negatives. So again it's hard to say.
But what really bothers me is that you got a reply from a no-reply address. What the actual fuck. You were there for an on-site interview, this is not the situation where you send people automated no-reply-click-this-link mails.
If their HR doesn't have the time to send a short personal mail (or an automated one from a HR address that doesn't look like it's automated) that might be a red flag on how they treat their employees anyways.
You can try asking them, we at my company were usually happy to tell candidates that didn't pass, why they didn't pass. But we also didn't blow off people with a no-reply mail that were far enough into the process to have been onsite.
The only advice I can give you is to move on and do the next interview. Don't let this get to you.
But what really bothers me is that you got a reply from a no-reply address. What the actual fuck. You were there for an on-site interview, this is not the situation where you send people automated no-reply-click-this-link mails.
If their HR doesn't have the time to send a short personal mail (or an automated one from a HR address that doesn't look like it's automated) that might be a red flag on how they treat their employees anyways.
You can try asking them, we at my company were usually happy to tell candidates that didn't pass, why they didn't pass. But we also didn't blow off people with a no-reply mail that were far enough into the process to have been onsite.
The only advice I can give you is to move on and do the next interview. Don't let this get to you.