Finding GZ will be the easy part. If all goes well you will be standing in front of a green route marker with the name of a hiking trail in front of you. You are now within 50m of the prize - all you need to do is solve the clue.
Take the route name that is now in front of you and assign a number to each letter, starting from 1 - 10 sequentially.
EX - if the sign reads GEORGE: G=1, E=2, O=3, R=4, G=5, E=6.
SIGN: C=1, _, _, _, _, _, _, - _, _, S=10
You will also need the following additional letters to complete the clue sentence:
W = 11, L=12, T=14, H=15, I=16, Y=16, E=17, T=18, G=19, N=20.
Now click the hint for the encrypted numbers that correspond to the letters above and from the SIGN.