Hey! I just fixed issue with invalid class when you used spigot instead of paper. I have tried it on my localhost and now it works. Also there was a little issue with the armorstand placement, which is also fixed and I have implemented a feature to customize the placement.
Please add these options to your configuration (config.yml)!
Code (Text):
robot:
offset:
x: 0.5
y: 3
z: 0.5