I'm running version 2.2.5 and it keeps crashing. The log file / Blame report says:

Failed to load structure nbt file from: atum:ruins/ruin18
The path represented by this is: data/atum/structures/ruins/ruin18.nbt
Most common cause is that there is a typo in this path to the nbt file.
Please let the mod author know about this so they can double check to make sure the path is correct.
A common mistake is putting the structure nbt file in the asset folder when it needs to go in data/structures folder.

Let me know if you need my full debug log or crash report

There is no ruin 18. You most likely have an old config. Change the ruin amount to 17 in the config, or delete the config to let it generate a new (If you haven´t made any changes yourself)