Proceduerally Generated Structures not naturally spawning.

Hey, I'm trying to make a structure that naturally spawn in a custom dimension that proceduerally generates a rougelike dungeon-esque layout. I followed the steps outlined in this video: https://www.youtube.com/watch?v=2sfqLgUR2Tw&t=1s but when I use the advice given in the comments to generate the dungeons via a seperate single block structure, no matter how I tweak the code it will only spawn the structure if I place the block manually. Any help on fixing this would be appreciated.