Click Driver Code and put Driver code in there.
When it's time to install an App, click Apps Code and install Apps code there.
--- Editorializing and opinioning now follow:
It's a bit of a mystery why we NOW have two places to add code. One strictly for Apps and one for Drivers YET, each can tell that you're adding to the wrong place. I understand how it started that way: SmartThings influence.
Time for some Hubitat superiority, just like with Iris v1.
(not holding my breath though.)