does apple scan for viruses

It is a scam. Apple would never send an email about scanning for viruses.  In a message Apple will always address you by your real name, never by your email address or Dear Customer. Also the sent-from address should be @apple.com or @itunes.com Additionally Apple does not send attachments.

Avoid phishing emails, fake 'virus' alerts, phony support calls, and other scams - Apple Support

Forward it as an attachment to reportphishing@apple.com

Well we can start by seeing what is installed on the computer. Please do the following:

Please navigate to the Mac App Store and download the free version of EtreCheck OR please click www.EtreCheck.com where you will find the app. Once you downloaded the free app and created the report please post it as your reply to this message. In order to post it, please use the following link for more detailed instructions on how to correctly include the results: 

https://discussions.apple.com/docs/DOC-250000211

We can then look for obvious issues that may be causing your problem

They don't and can't through the web; it's not possible to scan a Mac or iOS device through a web browser. If you take it to a physical Apple Store, they likely won't do anything other than run MalwareBytes for Mac, which you can do yourself.

macjack: The notice came in a web browser popup, not an email.

(175877)

Apple does not read or participate in these forums we are all end users like yourself. That being said, my opinion is that I doubt they care.

A pop-up huh? Thanks Niel, missed that.

@fprats - All such pop-ups are also scams.

That's what happens when you get old. 😎

Looks like you have malware installed. All the "possibly adware" probably are. If you don't recognize them delete them. Also as noted in the report your battery needs service.

You're welcome.