The cache is NOT at the posted coordinates. You must first complete "Zionsville History" Adventure Lab.
You can look up the Adventure Lab here
https://labs.geocaching.com/builder/adventures/details/26898603-f223-48a1-b53b-952004b7ddad
or the QR Code for the Adventure Lab is in the gallery.
https://labs.geocaching.com/goto/zionsvillehistory
At the completion of each lab stage you will see a letter with a number (Z=0). Place the numbers in the corresponding spots to reveal the correct coordinates.
N39 56.9AB
W86 1C.DE0
Once you complete "Zionsville History” Adventure Lab, you will then have the information needed to get the final coordinates for this mystery cache.