If you've come across the URL r2---sn-4g5lzney.c.2mdn.net and wondered whether it's something to worry about, here's the short answer: it's a Google-owned ad server subdomain. The main domain 2mdn.net belongs to Google's DoubleClick advertising platform, so this is infrastructure, not a store or a service you'd sign up for. The site itself returns a 404 error, meaning there's nothing to see or interact with. That's perfectly normal for these technical endpoints.
There are no indicators of a scam. The SSL certificate is valid, the connection is encrypted, and Google's networks are not known for hosting malware. The lack of a privacy policy or contact page is expected here – the parent company handles all of that. In short, there's no reason to treat this URL as dangerous, but also no reason to click on it expecting a real website. It's just a piece of the ad delivery system.