Okay, so you don’t have Adobe Flash installed? Because that too show its own messages about updates.
Ignore the web pop-ups, they’re one of the myriad ways they try to get folks to load junk, or to expose their credentials.
These same folks will claim to run anti-malware scans, or offer titillating photos (some of the earliest malware around was known as ILOVEYOU “I love you”, for how it tried to convince its recipients to access its contents) , or outrageous claims, “free” stuff, pretty much anything to get your attention, and get you to do something... unwise.
Your web browsers can be configured suppress some pop-ups, but the scammers do continue to work to find new and different ways around that—scamming is a bug business.
Recognize and avoid phishing messages, phony support calls, and other scams - Apple Support
Clearing Safari as mentioned above will clear out the malware trash, if the trash happens to get stuck in your web browser caches.
And FWIW, calling telephone numbers and sending email addresses can be spoofed / faked / forged.
