Implementing Structures for the first time

Hello, my name is Avila. I'm the Creative Director of HibiscusMC, a vanilla+ server that uses plugins and resourcepack to improve the vanilla experience.
I wanna add new structures to the server world gen. I've built them, watched a bunch of videos explaining jigsaw blocks, but i couldnt get it to work, idk what i'm doing wrong, so if any patient soul wanna help me i would be so happy.
 (here some pics of the structures, with custom blocks and plants)