Does anyone know how to make this works with a collection. I tries implementing a bounding box node and accumulate the max z dimensions but i cant make it work. This screenshot came from Chris in reaction to another question

Does anyone know how to make this works with a collection. I tries implementing a bounding box node and accumulate the max z dimensions but i cant make it work. This screenshot came from Chris in reaction to another question

Edit:

This was my solution but it doesnt work.