---
Calculator is working fine for me, both from the link you provided and from the link at the website. I'm adding a screenshot from
a game that has been played today on the
Roll Hunt Contest as an example.

To get that hash, the site uses the server seed and the first 3 bettors' seed and combines it. For the example I've provided, you can check it by yourself in
this SHA-512 Generator (for example)
dbdea3ef0af8dd6294ab7c72ae49e6e0cd579dac
948bf5576b6247d3a24ecfdb56055da756e2f057
ae6ec1d7b5bddd4953a11915cf9690a73192f8ef
399ce29ca1e9f0a05865c45b94490548a51cd1e9
Putting that together we get
dbdea3ef0af8dd6294ab7c72ae49e6e0cd579dac948bf5576b6247d3a24ecfdb56055da756e2f057ae6ec1d7b5bddd4953a11915cf9690a73192f8ef399ce29ca1e9f0a05865c45b94490548a51cd1e9
And the output of that is
ffd9dc8a1f768fca75ae75c51318adb3f552f5e77d036e5c1c9f21df182a248b0019da2230ee73d7e74e543a02faf654754967f3ebdd3b16e64ecf93604239a9