Norton scan missing possible malware?

Hello, I have question regarding a possible virus pop up I recieved while on my outlook/hotmail email account. 

I logged onto my email and as I was browsing emails, a pop up/window appeared with the Outlook logo. It said something about third party ads and you can opt out at any time just go to Outlook settings. Then there was a Reject or Accept button. There was no X to close the pop up and as outlook had just updated (I recieved a message when I logged in), I thought that this was part of their updated terms and conditions, so I clicked Accept on it. As soon as I did that, I felt uneasy. So I had Norton do a Full Scan, but nothing came up. I googled this to see if any one else had seen this and I only found this site:

https://learn.microsoft.com/en-us/answers/questions/1388865/how-to-get-rid-of-possible-scam-window-pop-up-when

I did another full scan Sat. morning and nothing came up. The scan took twice as long as usual (normally it's only 2 hours, this time it took 4).

Is this a scam pop up? If so, why is Norton not picking it up? What else can I do?

thank you for your help.

System is Windows 10.

it would be difficult to say for sure what the ad was without a screen shot or more info on it

there are some ads that are misleasding ( pop up ads) that claim various things such as , found malware, privacy concern etc...

some do look realistic

having it mention cookies would seem somewhat legit atleast as several sites i goto have that ( usually on bottom bar thing) click to accept all or manage option

just tried on msn and didnt notice this ( may not appear everytime)

but if all it was just a cookie notice ( we use cookies , accpet or opt out) than that should not be a concern

if it was something else that possible to be concerned