Hi Tien,
Why did you think that example is for GMAC not EMAC.
You can see as below:
Nhi_Nguyen_0-1690791499360.png
Nhi_Nguyen_1-1690791508466.png
This means that S32K344 just supports EMAC not GMAC and the example S32K344 was attached in the package is for EMAC not GMAC.
Best regards,
Nhi