Help with "Closed-chain-IK" lib

I have a glb of a 6 dof robotic arm and I am trying to create a robotic arm simulation. Came across this library. Couldn’t go any further with implementation.
Can anyone help me out in understanding the integration or a working example with code helps too.
I came across the demos, but couldn’t get hold of the code to understand it.

And also can I make it work with GLB model or do I need urdf?
If so how can i convert my .glb to .urdf.

Thank you