Have you read and tried the method I posted above with the link to the FAQ.
I used the abreviation “here” for this: https://forum.kicad.info/t/kicad-6-beginners-guide-to-personal-symbol-and-footprint-libraries/38738
The very last paragraph explains that footprint libraries are made the same way as symbol libraries.
That sparkfun tutorial doesn’t describe how to make a library, just how to make something to place in the library.
That Sparkfun tutorial is incorrectly titled.
This is their first sentence: This section will show you how to create your own local custom footprints