This is an offset cache.
At the posted co-ordinates you will find a rural icon, once used to move a critical substance, but now one assumes, for decorative purposes only. Careful observation at this object will reveal the numbers you need to continue on your journey. Use of the standard Letters to Numbers code is required at your first port of call.
At GZ you could be sharing your search area with children, as onsite evidence indicates they also play here at times. You will be seeking a 1 litre container holding a pen, log book and some small items suitable for exchanging.