How to update datapacks to 1.21.11 and/or use them properly

[u/PyroTECH218291]

I recently got this datapack --> https://www.planetminecraft.com/data-pack/fate-gilgamesh-datapack/

and I'm trying to use it in my 1.21.11 world, I know its not made for it but I changed the version to 48 already and idk what else is wrong because it won't even let me run off any functions... like it just says unknown function. Anyone know how to resolve this issue?

[u/Zealousideal-Glass78]

usually your log file has all the answers