The cache is NOT at the listed coordinate. To find the coordinates you need to solve a puzzle. It's recommended you complete Millie's Slides Adventure Lab.
https://adventurelab.page.link/rcex
Who can resist another slide? When it comes to Millie, resistance is futile!
The cache is hidden at S31 55.AB4 E115 51.CDE.
The values for A,B, C, D and E can be determined by completing the lab.