F-Secure Safari Browsing Extension

I installed F-secure anti-virus (free) from my Spectrum account, and it prompts me to install a Safari extension for browsing protection. This all takes me to the App Store, where I don't know what app to choose to have so I get a safe browsing extension to activate or turn on. Apple says that it doesn't support unsafe extensions as far as the F-Secure extension that it directs me to load. So, my iMac is deemed unsafe as far as browsing in Safari. I can use Firefox now, but I don't know what to do next. Help!