You have been scammed
There is ZERO chance that any *.exe virus can infect your Mac.
The fact that a remote tech accessed your machine and told you this tells me that either the tech didn't know what he was talking about (was he actually from HP?), or that its part of an orchestrated scam where malicious actors trick users into giving access to their systems under the guise of 'support', only to find they either infect your system with more malware, or they steal your data while they 'fixing' your problem.
either way, 100% DO NOT send this tech support person ANY money. You do NOT need Norton Security on your Mac. Even if you did, you could go and buy it from a retail store NOT via some sketchy tech support.
If you're still on the phone with them. hang up now.