You don’t need the EEPROMWriteAnything library. The functions used in the later examples are built in to the Arduino package. No need to download anything.
You do need to include the eeprom.h header file as shown in the last, simplest example, because it is not automatically included by the Arduino system (as is, for example, the math.h header file).
Relax, try things and read a lot. You just have a long way to go.