how to add 3d model to the scene using a screen button.

Hello everyone.

I would like to know how I can add an object in 3d by pressing a screen button in an augmented reality scene, I have tried and I have seen tutorials of similar themes but I have not managed it. I have been guided to do it with this:

but I'm failing to replace the domino piece with my 3D modeling, I suspect that something has to be modified in the script but for more I have tried I could not.

Please help.

first of all, Thanks.