You mean the old uGUICustomMarkerEngineExample example, right?
This is very deprecated (removed a year ago) and now you can do it this way:
https://infinity-code.com/atlas/online- … rawer.html

When using uGUICustomMarkerEngineExample, you cannot use marker events and you need to add listeners to UI elements yourself.

OnlineMapsMarkerBase

so that the OnMarkerClick method is not available. I tried creating my marker prefab as a button but the click handler doesn't fire.

I was able to get

OnMapClick

but it doesn't seem to contain any data on what is being clicked.

Any thoughts on how to do this? (Other than doing a custom raycast hit listener) Thanks!!