So, what does the code in the ‘ENTER NEW ITEMS’ button look like?
How is the data getting into the repeating panel? It only looks like you are making one checkbox and there are no other elements in the repeating panels ‘template’, see:
https://anvil.works/docs/client/components/repeating-panel
I made an app you can clone that shows an example of how one could use the data bindings for objects placed in the ItemTemplate form to add new items.
It has cards items placed side by side in the template, creating ‘columns’ as I think you are asking for.
https://anvil.works/build#clone:MCAHTDHMX5XEZMOP=LQN7F6V2FEUMVPS5WOKJKMEI