Schematic or symbol? Assuming “schematic” was meant to be “symbol” this sounds like an ancient outdated tutorial as .lib libraries are a legacy KiCad library format. Toss that tutorial out. Use this FAQ by jmk:
The official documentation for creating a new symbol library is here:
The official documentation for managing a symbol library is here:
It’s a little unfortunate that the latter precedes the former in the text.