There's no requirement to take formal notes, unless it's helpful to you! Some Squad Mods have found it helpful to keep some notes on each member of the Squad, so they remember their goals and can more easily build a relationship with them.

It may be helpful for the Squad to keep high level notes from each call, including any resources, websites, tools, articles, videos, etc that were shared; you can add any notes to the "Meeting Details" of each call by editing the Squad Curriculum.