@jcauevents - Did they mention what this was for? It actually looks like they are trying to get you to add a TXT file, which would be with your domain host provider.
Happy to help, but you'll need to obtain more information or share that with the forum so we can assist further.
Also, I have a tutorial video on how to add your Google Analytics tracking code to your squarespace website if you want to try that: https://agencyapex.co/how-to-add-google-analytics-to-squarespace/