I found these 4 good addresses all in Guatemala City. None have a postal code, just the country Guatemala listed. Put there are different zones, which may be like a postal code, but part of the address. 24 Avenida 2-20, Zona 15 Vista Hermosa I Guatemala City GUATEMALA Guatemala 5th Avenida 5-55 Edificio Euro Plaza, Torre 2 15 Nivel, Oficina 1504, Zona 14, Guatemala, Guatemala C.A.
It’s a funny thing but yeah, from all appearances it looks like there are no postcodes. I was checking this map https://worldpostalcode.com/united-states/california/san-diego where you can find any zip post in any country. But when it comes to Guatemala it says ‘unknown’.