I thought it may not be immediately obvious that the easiest way to create clone is no longer with a repeat loop.
All you need is a When ____ < ____ event like this. Your clones will be created & now automatically indexed. Then just put a custom Initialization block in When Game Starts and When Object is Cloned.
This also has the advantage of the previously used fast cloning method, where 2^n clones are created in n steps (since all existing clones participate in the cloning during each step, not just the original object)
Then just put whatever you want in the custom Initialization block. In this example I put a couple lines of code to create block lettering that reference the Clone Index & Total Clones traits: