cdncr90

I was on Facebook and it kicked me off, telling me I need to sign in again. When I signed in this screen popped up. Is this legit? I had a message pop up a few days ago on my computer saying it detected something and I need to download something right away to fix it. I'm hesitant to do things like that in case that is actually a virus, so I just closed it out. My Windows Defender Antivirus just finished a scan of my computer and says it didn't find anything. Should I be worried?