Screen Time missing on Macbook

Hi. I have a Macbook Pro 13" (early 2015) with High Sierra 10.13.6 installed and would like to use Screen Time on it. I use Screen Time on my phone and want to add my Macbook as a device. Apple Support directs me to System Preferences, but cannot find Screen Time there. Am I looking in the wrong place? If it's really missing, can I add it, and how? Thanks to anyone with a suggestion!