This cache is NOT at the posted coordinates!
The ADF(V)GX cipher uses a key square with the letters of the alphabet. In the case of the ADFGX cipher (the original cipher) the J is not used and replaced by the I, so the alphabet fits into the 5 x 5 square. Next every letter in the plain text is replaced by the combination of two of the ADF(V)GX letters using the key square. These combinations are positioned beneath the key word in rows. The rows are then alphabetically sorted by the key word and read vertically. This is how the encrypted text is found.
FAXDXADDXFGDXXFFFADXDAXFADDXXXGXXDA
DDAXDFADXFFFGDDFDDGDAXXGGFDAGADFDX
GDGAFXAAGGGAFFFDDDAGAXFXXFAFFFGADDX
FFXADXDFFFADDAGFAFDFXGDAAXGADDAFFD
You can validate your puzzle solution with certitude.